Diamond, who was officially recalled from Triple-A Rochester late Saturday night, was told before his start on Friday that he'd be getting called up by the Twins. He tossed three scoreless innings before he was pulled from the game.
Diamond, 25, posted a 2.60 ERA with 26 strikeouts and seven walks in 34 2/3 innings with Rochester.
"I was mixing up everything," Diamond said. "I was able to work down and get ahead of hitters. We had a good catching staff down there and were working on the same page, which was good."
Diamond started seven games with the Twins last season, posting a 5.08 ERA with 19 strikeouts and 17 walks in 39 innings. But he said he learned a lot from his experience in the big leagues, and it helped him this season at Triple-A.
"I remember taking to [Carl] Pavano a lot last year, and he goes deep into games, so I tried to take the same mentality into every game this year," Diamond said. "I've tried to keep it simple and not let the game speed up on me. So I've been able to throw strikes and attack hitters."