2018 MLB Draft Guide: Ballpark Factors

Baseball is unique. It’s the one sport where advanced statistics are brought into play more than any other. Whether its exit velocity, BABIP, FIP, swinging strike percentage, etc. these advanced numbers may be considered “over thinking” it by old school baseball purists, but it’s 2018 and arguing against mathematics and science is just silly. Football fields are 100 yards long and 160 feet wide. Basketball courts are 94 feet long and 50 feet wide. Hockey rinks are 200 feet long and 85 feet wide. The dimensions are the same throughout. Baseball parks vary. Each park features its own unique “zebra stripes.” There are domed stadiums and there are stadiums with roofs that can open up. There are parks with shorter fences and others with more expansive outfields. It’s important to understand what makes a ballpark more hitter friendly and what makes a park cater more to pitchers.

The Impact of Air Density

Air density is one of the biggest contributors in determining whether a ballpark caters to hitters or pitchers. Everyone knows Coors Field is arguably the best hitter’s park in all of baseball. That’s because of the elevation. It sits roughly a mile above sea level and features less dense (aka “thinner”) air.  Because of the less dense air the ball will naturally travel further. Now Coors Field isn’t the only ballpark at a high elevation, but it by far leads the pack by a wide margin.

Considering Coors Field sits 4,000 feet above all other ballparks, the air is significantly less dense. The thinner air in Denver decreases the resistance on batted balls, so they tend to travel farther. For the longest time the Rockies were the only team to implement a humidor for storing its baseballs. The general rule of thumb is storing them at 50% relative humidity and 70 degrees Fahrenheit. This will ultimately make the ball a little heavier and won’t be able to travel as far in less dense air. Keep an eye on Chase Field heading into 2018. Last season it was announced that they would be implementing a humidor midway through the season, but the league denied them and had to put it off until this upcoming year. So far there’s been no word as to whether or not they actually will use a humidor. If they do, it’ll be slightly more beneficial to pitchers if that’s the case.

Humidity and temperature also play a role in air density, but not nearly as much as elevation. The more water vapor that is in the air, the farther a baseball will travel. Water molecules weigh less than air molecules so the more water vapor there is (aka the higher the humidity) the less dense the air becomes. The same is true for temperature. The warmer it gets, the less dense the air is. This is why you can expect balls to travel further in the summer as opposed to when the season starts in April. As temperature increases molecules speed up and spread apart and occupy a larger volume, this results in less air density.

All in all elevation is the biggest factor and with Coors Field sitting at least 4,000 feet over any other ballpark it will always have an advantage for hitters. Temperature and humidity will fluctuate throughout the season for all ballparks, but elevation is the only constant and Coors Field literally stands above the rest.

Wind Factors

Naturally wind is an intriguing factor to look at especially if you’re a DFS player. If wind is blowing out, that could help hitters. If it is blowing in, then it’s beneficial to pitchers. Certain ballparks may have their own unique wind patterns. Up until about 2013, Globe Life Park in Arlington, Texas was a power hitter’s dream. The ball just seemed to fly out of the ballpark with ease. Perhaps the heat and humidity factors mentioned above played a part, but from 2008-2012 Globe Life Park averaged over 200 home runs each year. Why? In the summer the wind would blow in from the South from the outfield. It would basically be “turned around” at home plate because of the closed in structure behind home plate and it would go right back out to the outfield. In 2013, the Rangers did a renovation to the stadium and added the Capital One Club that opened the Northwest structure behind home plate. Because of this, the wind was no longer sent back to the outfield. After the construction there were 159 home runs at Globe Life Park in 2013.

Now Globe Life Park is still a very friendly hitter’s park. In 2017, according to Fantasy Alarm's Ballpark Ratings, it was top-five for hitters in terms of runs and home runs. Consider the renovations to be a minor setback, but it still caters well enough to hitters.

AT&T Park in San Francisco sits right on the bay so you’d assume a natural wind to be blowing in and yes that argument does make some sense. It’s only 309-feet to the right field foul pole, but the 25-foot-high wall takes a steep angle towards center field. Not mention wind blowing in from the water in the summer tends to push balls back towards the power alley where fly balls tend to be caught. These are just two examples of 30 major league ballparks. Naturally on a day-to-day basis the wind and weather changes, so check the weather each morning to get a feel for how the wind is acting for each game to get a bigger advantage in DFS.

Size and Area

Major League Baseball is well aware that home runs translate to more viewers. It’s a tried and true statement, but “chicks dig the long ball” can be applied to all genders really. And franchises want to put people in the seats. So it’s no surprise that the league wants to bring more offense to the game. Since 2012 the Padres, Mariners, Mets, and Marlins have all moved their fences in to increase home runs. In the case of the Marlins they not only moved their fences in, but also put in shorter fences. While this is obviously a move to increase home runs it potentially leads to a drop in extra base hits.

But home runs aren’t everything for offense. In looking at some of the ballparks with larger outfields there are some that stick out as hitter friendly parks. Coors Field, Chase Field, and Globe Life Park all feature some of the more spacious outfields in baseball and yet are still accommodating to hitters largely because of some of the factors listed above, but also more space in the outfield creates more alleys to drive the ball. As of 2015, there were eight ballparks measuring with at least 92,000 ft² of outfield space. Of those eight, the three listed above (Coors, Chase, and Globe Life) are known more for being hitter friendly. Comerica Park also boasts one of the larger outfields in baseball especially with its massive center field measuring at 39,900 ft² and yet it still graded out top-three for runs according to Fantasy Alarm's Ballpark Ratings.  Now some of the other ballparks with 92,000 ft² in the outfield are Minute Maid Park, Kauffman Stadium, and AT&T Park. Interestingly enough those three ballparks ranked 19^th or lower in Fantasy Alarm’s Ratings in terms of runs.

However, there are also smaller ballparks. Fenway Park’s outfield measures in around 83,500 ft² because of the heavily shallow left field due to the Green Monster that is over 37-feet tall. This becomes a target for right-handed hitters to try and hit one over the wall or at worst hit one off the wall and reach base safely. Yankee Stadium is notorious for its short right field porch. By far the shallowest right field in all of baseball, at 24,200 ft² it really plays as a hitter’s park. The Orioles (Camden Yards) and Reds (Great American Ballpark) both play in hitter’s parks because of the lack of foul territory as well as the hitter-friendly alleys in their shallow outfields.

Like the larger ballparks, the smaller ones feature a balance of hitter and pitcher parks. While Fenway Park and Yankee Stadium help out the bats, Tropicana Field, Minute Maid Park, and Safeco Field aid pitchers. So while certain features of differing outfields may benefit hitting over pitching the overall size of each park has little impact. In this case, size may not necessarily matter.

Playing Indoors

Currently there are six baseball teams with retractable roofs: the Arizona Diamondbacks (Chase Field), Miami Marlins (Marlins Park), Milwaukee Brewers (Miller Park), Houston Astros (Minute Maid Park), Toronto Blue Jays (Rogers Centre), and the Seattle Mariners (Safeco Field). Most of these teams have varying weather-related concerns for why they have retractable roofs. Miami and Seattle both have heavy rain concerns. Houston sits right on the Gulf of Mexico so humidity is a concern down there. Toronto and Milwaukee need roofs to accommodate for the colder months at the beginning of the year. Lastly the Diamondbacks don’t suffer from the same concerns as the other teams, but intense heat in the summer is the reasoning for keeping the roof closed to keep the temperature comfortable inside for fans.

Tropicana Field is unique in that it is the only ballpark with a fixed roof so it will never open. The Rays will always play their home games indoors as long as they call Tropicana Field their home. The Trop is not without its controversy however. There are four levels of catwalks inside Tropicana Field. Now depending if you hit these catwalks in fair territory you could either be at risk of being out or you could be rounding the bases for a home run.

If you hit one of the higher two rings, highlighted with blue circles, the ball is still in play and it can be caught for an out. If a batter hits one of the two lower catwalks, highlighted with a red circle, in fair territory then it’s a home run. The catwalks and their attached masts and light fixtures face criticism on a regular basis as they occasionally impact a few games each year. Another unique feature of the Trop is the amount of foul territory. There are only two ballparks with over 30,000 ft² of foul territory (The Trop and the Oakland Coliseum) and that extra space makes this ballpark more of a pitcher’s park because it gives the defense more room to catch foul balls. Add in the fact that the Rays play in a climate-controlled environment where wind and humidity don’t play a factor and this is a ballpark best fit for pitchers.

Now there are the other teams that have the option of opening their roof. And a huge thanks has to go out to Nicholas Chabot and his team at XML Team Solutions for helping us get the following splits for ballpark’s with their roofs open and closed.

Minute Maid Park

Safeco Field

Miller Park

Rogers Centre

There are two ballparks to address right off the bat: Minute Maid Park and Safeco Field. Safeco clearly prefers to keep the roof open, save for when it rains. Because of the high humidity during the summertime, the Astros prefer to keep the roof closed for the most part. But they do occasionally open things up if the weather is appropriate. When the roof is open, there is a 4.3% home run rate compared to 3.98% when it’s closed. There is a 24.36% hit rate with the roof open and a 25.37% hit rate when the roof is closed. The biggest difference is that power hitters benefit from the humidity when the roof is open.

Safeco has a reputation for a being a bit of a pitcher’s ballpark and perhaps the biggest takeaway is the home run rate for when the roof is open. The 3.97% home run rate with the roof open stands out compared to the 3.17% rate when the roof is closed. That may not sound like much right now, but there were 5,492 total plate appearances at Safeco last year. If the Mariners played all their games with the roof closed and the home run rate stayed the same then there would be about 174 home runs. If you take the same variables, with the exception for opening the roof there would be about 218 home runs. That slight 0.8% difference in the home run rate could possibly lead to 40 or more home runs.

Now traditionally, Miller Park has been an offensive ballpark. However, last year it had a bit of a regression as it ranked just 13^th in home runs, and 15^th in runs according to our ballpark ratings. But it’s a good park to look at because although there were more games played with the roof open than with it closed, it was a little more even compared to Minute Maid Park and Safeco Field. For Miller Park, the home run rates are relatively close at 3.85% with the roof open and 3.65% with the roof closed. With the roof open the hit rate is 24.75% compared to 26.11% with the roof closed. So while there may have been more hits with the roof closed it seems the open air can benefit the long ball in Milwaukee. Perhaps while the balls may travel further with open air thus increasing the amount of home runs, it may cause more line drives to hang up a bit to be caught.

In 2017 for Miller Park, the biggest difference was with strikeouts. With the roof open there was a 27.89% strikeout rate compared to a 24.55% rate with the roof closed. Perhaps 2017 was just a fluky season for Miller Park as it’ll still be a cornerstone park DFS players target when the Brewers are playing at home.

The Rogers Centre is probably the most even ballpark of them all when it comes to plate appearances in open air and closed roof conditions. Although there were still more open-air plate appearances the numbers suggest that it played as a more hitter-friendly park with the roof open. Here’s a breakdown of the rates below:

• Home run rate: Open – 3.81%; Closed – 3.64%
• Hit rate: Open – 25.52%; Closed – 24.63%
• Strikeout rate: Open - 23.41%; Closed – 24.25%
• Walk rate: Open – 9.75%; Closed – 9.04%

Across the board all those numbers benefit hitters when the Rogers Centre plays with the roof open. Don’t credit too much to the wind. The high-walled dome basically eliminates wind as a factor unless a towering flyball is hit. This park is worth keeping an eye on during a warm summer day in Toronto. If the roof is open the humidity is in play for power hitters.

Best Ballpark for Hitters in 2017

These rankings come straight from the Fantasy Alarm Ballpark Ratings page.

It’s worth mentioning that Minute Maid Park finished above Comerica Park even with five fewer home runs because there were three less games played at Minute Maid last year. Likewise there were three more games played in Miller Park last year (84 total) over Comerica, but since they tied for 217 total home runs, Comerica ranks higher. And for those curious Coors Field finished 15^th in terms of home runs.

Best Ballparks for Pitchers in 2017

Once again to clarify, Marlins Park grades higher than Kauffman Stadium, Busch Stadium, and SunTrust Park because it had three fewer home runs in two less games played.

Now the biggest takeaway to offer up is this: don’t just solely look at one year. A lot of factors could’ve taken place to lead to these results. Sure it’s not surprising that Petco Park, AT&T Park, and PNC Park all rank as some of the best parks for pitchers. Yes it’s surprising Coors Field didn’t crack the top-10 in home runs, but it still had the most runs scored overall. Fenway Park may not have yielded many home runs last season, but it still ranked top-five in hits and doubles. In 2016, the offensive numbers for Wrigley Field weren’t that great. Then it bounced back in 2017 and finished as an above average ballpark for offense. Don’t just look at one season. Look at trends from previous years. Sure there will be statistical outliers, but you’ll notice the general trends of which ballparks are better for hitters and which are better for pitchers.

Chase Field Humidor (Updated 2/16/18)

**With the announcement from the Arizona Diamondbacks that they will use a humidor for baseball storge in the 2018 MLB season, Dan Malin has updated the Ballpark Factors piece with a specific add-on for Arizona players.

Earlier this offseason for the 2018 MLB Draft Guide I published a piece on Ballpark Factors.Throughout the piece I touched on a variety of factors such as field area & size, elevation, humidity, etc. As a small note I briefly mentioned that Coors Field is currently the only park in Major League Baseball that utilizes a humidor to store baseballs. And it was also briefly mentioned during the 2017 season the Arizona Diamondbacks were considering installing one as well, but MLB shut that down because they were considering making the change too late into the season. Well as we gear up for the 2018 season, news has come out that the Diamondbacks will indeed install a humidor. Now take a deep breath because this could be a big deal.

Humidors are typically meant to store cigars. The purpose of which is to keep them from drying out, but by storing them in an environment where you want them to absorb moisture you also don’t want them absorbing too much moisture. In Arizona’s dry, desert environment the baseballs don’t have much moisture. They’re a bit lighter and fly off the bat easier allowing for harder contact. Plus they bounce a little more. By storing the baseballs in a controlled environment they’ll be a little heavier because of the moisture they absorb. Don’t confuse this with the balls being soaking wet. That’s not the case, but it’ll make enough of an impact for fantasy purposes.

In April 2017, when rumors were swirling about a Chase Field humidor, Dr. Alan Nathan published an article for the Hardball Times. To sum it up briefly, the biggest takeaway was that he predicted a 25-50% drop off in home runs if the D-Backs chose to go the humidor route. That’s wild considering Chase Field is considered one of the best environments for hitters. In 2017, there were 215 home runs hit at Chase according to Fantasy Alarm’s Ballpark Ratings. Now a 50% drop off in home runs seems excessive. That means there would be over 100 fewer home runs hit in Arizona in 2018. But even the floor of Dr. Nathan’s prediction is surprising. A 25% decrease would still mean 50-55 less home runs.

Impact on Hitting

The biggest question has been how will this impact Paul Goldschmidt? To be honest Goldy might be the only person exempt from the humidor impact. Last season Goldschmidt hit 20 of his 36 home runs at Chase Field. He scored 72 runs at home compared to 45 on the road. He also hit 23 doubles at home compared to just 11 away from Chase Field. So yeah the guy clearly hit better at home, but don’t discount his road numbers either. At Chase Field last season he had a 47.3% hard contact rate while his hard contact rate on the road dipped to 41.6%. Now a heavier ball may induce less hard contact and a little more soft contact, but even if it drops somewhere closer to his road splits he’s still worthy of being taken in the first round. He’s still a phenomenal hitter with the ability to swipe at least 15 bags. His ADP might drop him down a little bit in the first round, but this shouldn’t scare off fantasy owners.

Now if only there was as much confidence in a guy like A.J. Pollock. Pollock played in only 112 games last season and hit 14 home runs, nine of which came at home. When healthy, Pollock is considered a 20/20 guy especially due to the hitting conditions in Chase Field. Unfortunately for him this change for Chase may impact him quite a bit. Last season Pollock generated a 32.4% hard contact rate on the road, but at home it was 37.6%. His HR/FB ratio was a little over 14% at home while it was around 10% on the road. Pollock’s ADP should take a hit with the installation of the humidor. His ability to steal bases makes him an intriguing grab later in drafts, but if he can’t stay healthy he won’t reach 20 home runs or 20 steals.

The same can be said for Jake Lamb who hit 16 of his 30 home runs last year at home. Lamb’s numbers will be pretty difficult to sustain anyway. He hit just .246 last season at home and his hard contact rate was actually better on the road at 38.4% compared to 33.2% at home. Hitting a heavier ball at home could potentially lower his hard contact rate even more and he could end up grounding out more.

It’ll be interesting to see what happens with J.D. Martinez. So far he has yet to sign with the Red Sox and it sounds like that deal may not even happen. If Martinez does go back to Arizona he may see a slight drop in his numbers, but there would be reason to remain optimistic like with Goldschmidt. Martinez had a ridiculous .741 slugging percentage in 2017 with Arizona. Not only that, but once he was traded to Arizona last season he yielded a 50.9% hard contact rate and a HR/FB ratio of 37.7%. He hit 29 home runs in just 62 games with the Diamondbacks last year and he averaged more than a RBI per game. If the Diamondbacks are able to bring him back then he may be worth still drafting higher regardless of the new hitting conditions.

Chase Field: A Pitcher’s Paradise?

To insinuate it would become a pitcher’s paradise may be an overreaction or an exaggeration, but if a humidor could have hefty negative effects on offense, than logic stands to suggest it would benefit the pitching staff.

Zack Greinke had a rough introduction to Chase Field in 2016. After signing a lucrative contract he debuted with Arizona to a 4.37 ERA (4.12 FIP) and just a 7.60 K/9. Fortunately he did finish that season strong and it carried over to 2017 where he finished fourth in the NL Cy Young voting by going 17-7 with a 3.20 ERA (3.31 FIP) and 8.56 K/9. The surprising thing is that he actually pitched better at home last season.

Considering he is still one of the best pitchers in the game even at 34 years old, there’s plenty of reason to suspect big things from Greinke this year.

Other Diamondbacks pitchers should get in on the fun too. Zack Godley is currently considered a bit of a sleeper right now despite have a pretty strong 2017 campaign. He boasted a solid 9.58 K/9 over 155 innings of work, but he still gave up 3.08 BB/9, which you’d like to see come down a bit. Godley had an exceptional 56.5% groundball rate at home, which likely explains why opposing hitters hit just .194 against him at home. Science suggests he could induce even more contact with a heavier ball. For that reason, he should be on your radar when drafting.

Robbie Ray had the highest hard contact rate (40.4%) among qualified pitchers last season and that number was even worse at home (45.1%). Ray is certainly the kind of pitcher who could use a break at home and this humidor move could help him greatly. Last year he had a 4.08 ERA (4.45 FIP) at home while on the road he fared much better with a 1.86 ERA (3.09 FIP). He’s still a high variance pitcher considering he averaged 12.11 K/9 last season, but that also came with a 3.94 BB/9. The good news is that with a heavier baseball he should have fewer outings where he gets lit up.

Don’t sleep on Patrick Corbin either. His struggles came mostly on the road, but he’ll be worth a flyer in the late rounds or you could add him as a streamer off waivers if you have to.

Overall it’s a little bit surprising this news isn’t getting more attention. When Coors Field adopted a humidor in the early-2000s the offensive drop off was pretty noticeable. But in comparison to other parks, the extremely high elevation at Coors Field still makes it hitter friendly. Chase doesn’t have a 5,000+-foot elevation to lean on. This move could have a significant impact on Diamondbacks players and should be accounted for a little bit more as fantasy owners prepare for draft season.

For more on the Chase Field Humidor Effects, check out Greg Jewett's article also here on Fantasy Alarm.