BALTIMORE – Sunday's start might rank as the second-most exciting day of Pedro Hernandez's life. But it will never top the first.

That came last July 28, when his wife Jackie gave birth to Bianca, their first child, at 8:30 a.m. The baby was 90 minutes old when the lefthander got a phone call from White Sox General Manager Rick Hahn, telling him he had been traded to the Twins in the Francisco Liriano deal. The trade was disconcerting, but it's worked out. Hernandez had a strong spring training, allowing no runs in 11 innings, and nearly made the team. But he would have been a reliever, and "I didn't think he was quite ready for that yet," manager Ron Gardenhire said.

So the Twins sent Hernandez to Class AAA Rochester to join the rotation. Before he could throw a pitch, though, he was needed in Minnesota when Cole De Vries came down with tightness in his right forearm.

De Vries was placed on the disabled list Sunday, while Hernandez will make his second major-league start — and the 23-year-old Venezuelan is certain it will go better than his first. He gave up eight runs over four innings to Boston in his only big-league appearance for Chicago last year. Now?

"This year, I'm prepared mentally, 100 percent," Hernandez said. "This game is for my first child. So I feel really good. Bianca, she's my baby — right now, she's my motivation.""

Still not ready

Darin Mastroianni never had opened a season in the majors before, so he was understandably energized for Monday's first game. He went through he normal pregame preparations, then did a lot of running under the stands as the game went on to stay loose in the 35-degree weather.

That might have been a mistake, Mastroianni admits now.

"I woke up Tuesday in a lot of pain," he said. "If we had a game that day, I wouldn't have been able to play."

That's because of a deep bruise in his left shin, an injury he suffered by fouling a ball off his leg on March 25. He thought the injury would heal in a day or two; now it's been nearly two weeks, and he's still not certain he could play nine innings on it.

"If [Gardenhire] needs me to pinch-run, that's no problem. If he needs me to play the outfield [as a defensive replacement], I can do it," Mastroianni said. "But the last three days, going out for [batting practice], I shag fly balls during three groups, and I couldn't walk on it afterward. I'm trying to get where I can play nine innings, and I can barely get through 45 minutes right now."

His condition is improving, though, Mastroianni said, and he's hopeful of being ready in Kansas City to start giving the other outfielders a day off.

Etc.

• Gardenhire likes having three catchers around, just in case, but reluctantly sent Drew Butera to Rochester near the end of spring training, figuring it would be better for Butera to get regular at-bats. But Butera was hit by a pitch in his first at-bat on Friday, breaking a bone in his left pinkie. That's an injury that will require four weeks before he can swing a bat again.

• Tyler Robertson, who surrendered Chris Davis' game-winning grand slam one night earlier, was sent to Class AAA Rochester after Saturday's game. The Twins wouldn't say who is being called up, but righthander Anthony Swarzak is eligible to come off the disabled list, and has pitched well in tune-ups in extended spring training in Fort Myers. He also tweeted "Leaving Fort Myers" on Saturday.