The Phillies' No. 3 prospect struck out a career-high nine batters over eight innings against Class A Advanced Jupiter, allowing just one run and leading Clearwater to a 4-2 victory. Colvin allowed just three hits and one walk in the contest.
"It's really just being comfortable with my mechanics," he said. "I've been working on with our pitching coach, Dave Lundquist. Mainly, all my pitches were working, and I was throwing everything for strikes. I was repeating my mechanics and everything felt good."
Colvin, a seventh-round pick in 2009, emerged as one of the Phillies' best prospects last year when he pitched for Class A Lakewood. He posted a 3.39 ERA and struck out 120 batters, ranking fourth in the system in both categories.
The 20-year-old right-hander suffered a back injury in Spring Training this season, which limited him to just two innings in his season debut April 10. He stayed off the field for over a month, not returning until May 13.
"It kind of fired up during Spring Training with the heat and everything," Colvin said. "It was a tight lower back, maybe a muscle strain. It progressively got worse, which made me change a few things mechanically."
Since coming back, Colvin has put together a 3.67 ERA in 12 games, despite a pitching motion that had been altered by his injury. He thinks he has progressed greatly in his past two outings, in which he allowed just one earned run over 14 frames.
"I couldn't say it has [gone smoothly]," Colvin said. "At the beginning, I was fighting bad habits that I created even though my back felt good. I'm finally back on track and everything feels the way it should.
"We had one of our higher-ups come in and he pinpointed a few things, along with [Lundquist]. I was stabbing in the back a little too much. The last two outings, I've been focusing on that. Not really [to say] that was the only thing that was wrong, but that's definitely something that helped me progress the last two starts."
On Monday, Colvin (2-3) started and ended strong. He retired 12 of 13 batters at one point between the first and fourth innings, and he did not allow a hit over his final three frames. His eight innings represented his longest outing this season.
"Just the way I felt was the best I've felt all year," Colvin said.
Now that he has fixed his mechanical issues, Colvin's aim is to maintain the success that he's enjoyed recently.
"Just continue how I'm doing," he said. "Stay with the mechanics I have right now, listen to my pitching coach and stay on track for the rest of the season."