The left-hander's fastball velocity in his first two starts has been down about 2.5 MPH from his average velocity last season, according to Evan Grant of the Dallas Morning News.
Minor was seen on Fox Sports Southwest's broadcast of today's game speaking with a member of the club's training staff before being lifted after only throwing 83 pitches.
It's unknown if he's suffering from any sort of injury. Rangers manager Chris Woodward will likely be asked about his health following the game.
This is a developing news story.