Rockies Opening Day starter Jorge De La Rosa labored, giving up four runs on four hits -- including Gennett's homer -- in three innings. De La Rosa let out a frustrated scream when he walked Ramon Flores to force in a run in the third. De La Rosa threw 68 pitches in his final tuneup for the regular season and finished Cactus League play with a 6.10 ERA.
"I wished I could have finished stronger than that," said De La Rosa, who will start Monday against the D-backs at Chase Field in his second career opener. "I walked too many guys and gave up too many hits. I don't have the results that I want, but I have to work to get better."
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Gennett has had success this spring against left-handed pitchers like De La Rosa.
"It wasn't a big sample of at-bats, but he certainly had some good at-bats against them," Brewers manager Craig Counsell said. "He probably had seven or eight plate appearances against lefties, but he started against some good pitchers, so I'm glad he got some results."
Gennett, a left-handed batter, has platooned most of the past two seasons. Could that change in 2016?
"That's a decision we're going to have to make," Counsell said. "We haven't made it yet. We've talked about it. He's not doing anything to hurt his case, that's for sure."
Brewers starter Ariel Pena, who is awaiting word on whether he'll receive the final bullpen spot, started and held the Rockies to one run on three hits in three innings.
Arenado's homer came during a three-run sixth, which also included Minor League second baseman Pat Valaika's RBI double, against Brewers relief pitcher Blaine Boyer.
Brewers left-field prospect Brett Phillips kept the game tied in the eighth when he fielded Rockies prospect Raimel Tapia's fly ball and threw out Tim Smalling at the plate.
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Up next for Brewers: The Brewers packed up Maryvale Baseball Park on Wednesday and headed for Houston, where they will play exhibitions against the Astros on Thursday and Friday. Ryan Braun is expected back in the lineup for Thursday's 7:10 p.m. CT game against the Astros, with Jimmy Nelson on the mound. The game will air on MLB.TV, the Brewers Radio Network and Gameday Audio.
Up next for Rockies: Lefty Kyle Freeland, the Rockies' top pick and the eighth overall Draft choice in 2014, will return to camp and start Thursday's game against the D-backs at Salt River Fields at Talking Stick at 1:10 p.m. MT on Gameday Audio. Freeland, ranked as the Rockies' No. 8 prospect, struck out three and gave up one run in two innings against the Reds before being reassigned to Minor League camp as a non-roster player. Righty Chad Bettis will start in a Minor League game Thursday.