The Nationals prospect continued his hot start to the season Wednesday, yielding just one unearned run over nine innings as the Double-A Harrisburg Senators to a 7-1 win over the Altoona Curve.
Rosenbaum struck out nine while giving up just four hits and without a walk en route to the first complete game in the Eastern League this year. He tossed two nine-inning efforts last season, both for Class A Advanced Potomac.
"Really my changeup, my sinker, pretty much everything [was working,]" Rosenbaum said. "I was really happy tonight that I was able move my fastball in and out. I was in sequence with my catcher Devin Ivany, I only shook him a couple times. We were on the same page most of the game."
Rosenbaum allowed singles to Tony Sanchez and Kelson Brown in the first three innings, but went on to retire 13 straight batters after that. The streak ended with two outs in the seventh, when Sanchez again singled on a line drive to right field. Adalberto Santos then reached on a fielding error by shortstop Chris McConnell, while Elevys Gonzalez followed with a single of his own to plate the Curve's only run.
"After the error, I was like 'So what? Just get back on there and make another pitch,'" Rosenbaum said. "That's the mindset I've been trying to take after errors -- that's just part of baseball, it happens."
Rosenbaum was perfect for the rest of the game, retiring four of the final seven hitters he faced via the strikeout. On the whole, he excelled at keeping the ball on the ground, generating 14 ground-ball outs and only one flyout.
"Just try to keep the ball down in the zone, that's all they preach to us," he said. "Just try to live at the knees. A couple times, I came up in the zone when I was ahead just trying to get a swing-and-miss, but I was able to stay low. It gave my infielders a chance to make plays, which was great. It gave me a lot of confidence."
Tim Pahuta and Chris Rahl both had strong games for the Senators, combining for four hits, including two home runs, and five RBIs. The pair also crossed home plate three times.
A 22nd-round pick in 2009, Rosenbaum has thrived throughout his professional career, compiling a 2.34 ERA in 365 innings. Last year, he put together a 2.59 ERA in 132 frames for Potomac -- the highest ERA of his career at any level -- and then went on to post a 2.29 mark in 39 1/3 innings at Double-A.
So far this year, the product of Xavier University has gone 2-0 with a 1.25 ERA through his first three starts. He has fanned 16 in 21 2/3 innings and has yet to issue a free pass after walking 52 last season.
"Last year, I had a lot of trouble controlling my fastball," Rosenbaum said. "The year before, I could really put the ball where I wanted to. Last year, I couldn't. I had to figure out how to throw my other pitches. That's all part of the development process. This year, I worked really hard to get back to where I was with my fastball and luckily, I found it. Everything's been going well so far."
For the rest of the season, Rosenbaum simply hopes to continue the success that he's enjoyed so far.
"The ultimate goal from this point, since we're close, is the big leagues," he said. "But I just want to keep doing what I'm doing, stay consistent, keep pounding the strike zone and mixing all my pitches up. Just continue what I'm doing. That's all you can ask for."