CHICAGO -- Guys like Justin Morneau and Joe Mauer would get plenty of nods as the Twins' most valuable pieces, but there may be no one more indispensable in the lineup than Clete Thomas.
Without another true center fielder to back him up -- Darin Mastroianni, the most likely candidate, is on the 60-day disabled list recovering from left ankle surgery in May -- the spot belongs to Thomas. Backup catcher Chris Herrmann, who actually has as many career games in the outfield as he does behind the plate, is currently the team's next-best option.
"I'll let you know when it happens, how important it is [to not have a true backup center fielder]," manager Ron Gardenhire said. "Right now, I tend not to think about that stuff. As the game goes along, I know this: Clete won't get pinch-hit for or pinch-ran for. He'll have to take himself out."
Oswaldo Arcia also has experience in the Minors playing center, but he is best suited for a corner-outfield spot. Thomas, too, has appeared in left and right more than center, but he is still experienced in the middle spot. However, his batting average against left-handers is 38 points lower than against righties.
"I don't know if there's anxiety, but you'd like to have more options," assistant general manager Rob Antony said. "When you're facing a tough lefty, it'd be nice to be able to throw Mastro in there and give Clete a day, or be able to mix and match a little more and give Gardy a little more flexibility."
There's more to the situation than simply Mastroianni's health. The 27-year-old, health-wise, is just about ready to return, but he's having trouble hitting in the Minors during his rehab stint. Over 11 Minor League games, he's 5-for-29. This week with Triple-A Rochester, he's 0-for-12 with two runs, two RBIs, one walk and four strikeouts.
Mastroianni is eligible to be activated Thursday.
"I don't think you can take anything for granted," Antony said. "If he goes 0-for-the-rest-of-the-week and he's not swinging the bat at all and doesn't look like he's ready to help us, then he could be optioned. But the main thing is he's healthy right now and we just want him to get some hits and be ready to hit up here."
Joey Nowak is a reporter for MLB.com. Follow him on Twitter at @joeynowak. This story was not subject to the approval of Major League Baseball or its clubs.