Arenado, David Dahl and Raimel Tapia homered to lead the Rockies over Freddy Peralta and the Brewers 11-6 Thursday for a four-game split.
Arenado had three hits, including his ninth home run this season. Dahl finished a triple short of the cycle for the Rockies, who outscored the Brewers 22-10 in the final two games of the series. Colorado tied season highs for runs and hits (14).
Arenado is batting .343 (23 for 67) with a 1.196 OPS in his last 16 games, raising his average to .297.
''I'm pretty fortunate to feel like I am right now,'' he said. ''Early in the season I wasn't doing good at all. I was just happy I'm feeling better now, was able to drive the ball out, hit the ball hard.''
Colorado has won 12 of 17 following a 3-12 start. The Rockies scored 46 runs in their first 16 games and 101 in their last 16.
''I think the guys understand the length of the season and eventually things were going to turn,'' manager Bud Black said. ''The challenge is to keep the momentum, keep the everyday focus and intensity at a level where we're in every game. I think our talent will show up.''
Jon Gray (3-3) allowed seven runs and seven hits in 5 2/3 innings with nine strikeouts. He became the first Rockies pitcher to win while allowing five runs since Chad Bettis against Texas last June 15.
Peralta (1-1) made his first appearance since April 15 following a stint on the injured list caused by a sore right shoulder. He fell behind 7-0 by the second inning and gave up nine runs - six earned - eight hits and three walks in four innings. His short outing put more pressure on a bullpen taxed by nine innings Wednesday after starter Chase Anderson was scratched because a callus ripped on his right middle finger.
''We used the bullpen a lot yesterday,'' Peralta said. ''So I feel bad because I only went out there for four innings.''
Ryan Braun homered for Milwaukee.
Mark Reynolds hit a three-run double in a four-run first that included Tapia's RBI single. Dahl hit an RBI single in the second and Arenado followed with a two-run homer for a 7-0 lead.
Milwaukee closed in the third when Lorenzo Cain hit an RBI double and scored on Mike Moustakas' single.
Milwaukee allowed three unearned runs as SS Orlando Arcia and 3B Travis Shaw made errors.
''We played a poor defensive game,'' manager Craig Counsell said.
Brewers: RHP Taylor Williams was recalled from Triple-A San Antonio. RHP Jacob Barnes and LHP Donnie Hart were optioned to the Missions
Rockies: Chris Rushin (back strain) and Jake McGee (sprained left knee) could start minor league injury rehabilitation assignments soon. Manager Bud Black said. Rushin will throw to hitters Saturday and McGee on Tuesday.
Rockies: RHP Tyler Anderson (0-2, 11.34 ERA), who starts Friday at Arizona, allowed a career-high three home runs against Atlanta in his previous outing but struck out nine.
Brewers: RHP Brandon Woodruff (3-1, 5.17 ERA) starts the opemer of the series against the New York Mets. Woodruff held the Mets to a run while striking out six over five innings in his last start.
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