Six days after their 2012 first-round pick suffered a potentially season-ending injury, the Twins' 2013 first pick has potential injury issues, too.

Kohl Stewart, the 19-year-old righthander who was taken fourth overall in the 2013 draft and was now pitching for Class A Cedar Rapids, left Tuesday's start in the second inning after he was unable to throw his fastball harder than 88-90 miles per hour, according to farm director Brad Steil.

Stewart, 3-5 with a 2.42 ERA this season, just returned last week from a shoulder injury that kept him sidelined for nearly a month. He gave up only three hits and one run over four innings in his return last Wednesday, the same day that outfielder Byron Buxton, the team's top prospect, suffered a season-ending concussion in a collision at Class AA New Britain.

But Tuesday, Stewart faced only eight batters, gave up three hits (including a home run) and a walk, and was removed "as a precaution," Steil said. Stewart routinely reaches the mid-90s and above when he's healthy.

Stewart was placed on the disabled list in mid-July after feeling shoulder tightness following five shutout innings against Lake County. He came to the Twin Cities for a magnetic resonance imaging exam, but no structural damage was found and Stewart, who received a $4.5 million signing bonus, was cleared to return.

Stewart was shut down early last year, partly to limit his work in his debut season, but also because of shoulder problems that the team considered minor.

Stewart was "very tight-lipped" about his shoulder after the game, saying only that he felt bad but tried to pitch through it, Cedar Rapids Gazette reporter Jeff Johnson said via Twitter.

'Check the ball'

A day after being ejected by umpire Chris Segal, Ron Gardenhire still didn't understand why. For one thing, he didn't curse, the Twins manager said, adding, " 'Check the ball' should not get you thrown out." But it did, and Gardenhire spent the next eight innings in his office, watching on television.

"That's a long time [to] have to sit in my office and feel like you've been put in a corner at school," he said.

Gardenhire had argued that a Joe Mauer foul tip had hit the ground, so Segal should not have called him out. Mauer and Gardenhire insisted the umpire examine the baseball for a scuff from the dirt, but Segal refused. "Under those circumstances, it was pretty common sense," Gardenhire said, adding that he believes such plays should be reviewable under the game's new replay rules. But he finally gave up and returned to the dugout.

That's when the next batter, Kennys Vargas, also requested that the ball be checked, not because of Mauer's play but because a pitcher can make a scuffed ball break. Again, Segal refused, and the Twins bench loudly complained. "You've still got to check the ball. It hit the dirt," Gardenhire said. "Everybody has the right to ask that. Except me."

Etc.

• Mike Pelfrey won't pitch again this season, General Manager Terry Ryan said, because he won't be ready to return from May elbow surgery until the season's nearly over. He will be in the mix for next season's rotation, Ryan said.

• Jose Berrios, the 20-year-old Puerto Rican righthander, has a combined 2.37 ERA at Class A Fort Myers and AA New Britain this year, but he's not a candidate for the Arizona Fall League, as Ryan said the Twins don't want Berrios to pitch much more than the 125 innings he's already thrown.

• Twins coach Joe Vavra has rejoined the team and intends to travel, too, as he awaits mid-September hip-replacement surgery. He's not the only one in the dugout hurting lately; batboy Dom Frost missed two games after injuring his back.