Sore and frustrated, but not downcast. That's the latest word on Rockies shortstop Troy Tulowitzki. Tulowitzki went on the 15-day disabled list Thursday with a strained left groin, the team not wanting to risk an even worse injury. "He's good. He understands that this is not an injury you fight through," Jason Giambi, Tulo's closest friend on the team, said before Friday's game. "He understands that he's too valuable with his bat and his glove to risk it. He's matured to the point where he understands this is part of the game." Tulowitzki and Giambi worked out together in the offseason, with Tulowitzki paying special attention to his flexibility, hoping to avoid a leg injury. Does that make Tulowitzki even more discouraged? "I wouldn't say that," Giambi said. "But I think he's bummed because he was starting to get hot. Who wouldn't be bummed?" Tulowitzki had 10 hits in 24 at-bats before going on the DL. Of his eight home runs this season, four came during his last 10 games as he lifted his average from .262 to .287.