Firing a fastball that tops out around 96 mph and a nasty slider, Wily Peralta has arguably the best pure stuff in the Milwaukee Brewers' starting rotation.

But at just 23 years of age and with only five major-league starts under his belt coming into the season, the big right-hander finds himself way behind the curve when it comes to experience.

Peralta's first opportunity in 2013 to try and strike a balance between the two came on Wednesday night at Miller Park, in what wound up being a 7-3 Brewers loss to the Colorado Rockies.

Peralta turned in the longest outing by a Milwaukee starter so far on the young season at 5 1/3 innings, and kept his team in the game by allowing four earned runs on six hits and three walks.

But he also allowed four of the six leadoff batters he faced to reach base, and two of those came around to score in what was a 4-2 deficit for the Brewers when he departed.

"He was behind in the count," manager Ron Roenicke said. "First-pitch strikes were not good. He's got great stuff, but he's got to learn to get it over the plate, get ahead of hitters. These guys right now, they're pretty hot swinging the bat. But we've got to do a better job of pitching."

Peralta came in on the heels of an exhibition start against the Chicago White Sox late last week. He went 4 1/3 innings in that one, allowing four hits, two earned runs and three walks to go along with three strikeouts.

He was throwing to a familiar face behind the plate in Martin Maldonado, as the two worked together frequently the previous two seasons both in the minor leagues and again in Milwaukee when Peralta was called up last September.

It appeared as though Peralta might suffer the same fate as Yovani Gallardo and Marco Estrada before him after needing 19 pitches to get through the opening inning. Colorado leadoff hitter Eric Young Jr. worked Peralta harder than anyone, seeing 10 pitches before walking to open the game.