Why not Castro for rookie of the year?

Cubs shortstop Starlin Castro didn't want to talk about possible rookie of the year honors after another big game Wednesday, but others did.

Castro singled twice, doubled and tripled in the Cubs' 15-3 victory over the Brewers. The 4 hits were a career high for Castro, who came to the big leagues on May 7. So far, he is hitting .318 with an on-base percentage of .364, a slugging percentage of .458, 3 homers and 32 RBI.

There will be stiff competition in the National League for rookie of the year votes. The Braves' Jason Heyward was the early favorite, and the Giants' Buster Posey has come on. But why not Castro?

"Why not? Why not?" said Cubs manager Lou Piniella. "He's been up here since the first week of May or so. He's been in the lineup every day. He's hitting over .300. He does a nice job at the shortstop position. Yeah, I don't see any reason why he shouldn't."

Castro played it low-key.

"I feel good," he said. "When the call-up (came), I felt a little bit of pressure. But now, I feel better."

But he's not thinking about postseason awards.

"No," he said. "Just play."

Third baseman Aramis Ramirez went to bat for Castro.

"He's got better numbers than anybody," Ramirez said. "The other guys just have more numbers. He's got better numbers."

More rookie doings: Rookie right fielder Tyler Colvin hit his 17th home run, a solo drive to right field in the third inning.

That ties him with Mel Hall for the third-most homers by a left-handed hitting Cubs rookie. Billy Williams, a left-handed hitter, holds the franchise rookie mark, with 25 in 1961. Walt Moryn had 23 in 1956.

Numbers game: First baseman Derrek Lee picked up the 1,800th hit of his career with a seventh-inning single. He hit the 400th double of his career in the eighth.

Catcher Geovany Soto had 5 RBI. He has driven in 9 runs in his last seven games and 16 in his last 14. The 5 RBI were the most since he drove in 7 on Aug. 26, 2008 at Pittsburgh. Soto has a hitting line of .286/.398/.519 and 50 walks, tying him with Lee for the team lead.