After being released from the Giants' Double-A affiliate at Richmond last July, Heston didn't sign with another organization while on the mend from surgery. Given that he'll be 32 years old in April and had modest career numbers at the MLB level prior to requiring the major arm operation, Heston may have settle for a minor-league deal even if he looks good during his showcase.

Heston opened the season at Triple-A Sacramento, covering 3.1 innings in an April 9 start. He has been sidelined with the injury ever since, though he appears to be closing in on a return from the 7-day disabled list after beginning his rehab assignment June 20.

Heston spent the 2017 season bouncing around between a trio of organizations, finally finishing the campaign with the Twins' Triple-A affiliate. The 29-year-old will return to San Francisco, where he spent the first eight years of his career, up until last season. In total, he's pitched in 41 major-league games but has only appeared in seven over the last two seasons, and will likely begin this upcoming year at the Triple-A level.

He pitched five innings for the Twins' GCL team on Monday, clearing the final hurdle on his road back from a bout of shoulder tendinitis. Heston has posted a 7.63 ERA with Rochester, and he's mostly struggled with other affiliates this season. Further, the 29-year-old is not on the 40-man roster, so he will need to finish strong over the rest of August to have a chance at a September callup.