If Tulowitzki comes back strong in the middle of June, this shouldn't hurt the Rockies much. But they're already 11½ games out of first place, and Tulowitzki's been fantastic lately, with four home runs and 11 RBI in his last nine games. And after getting off to a shaky start in the field -- he's already made more errors this spring than he made all of last season -- he's gotten back to his usual self, defensively.
In the short term, it looks like Marco Scutaro will play a lot of shortstop, shifting from second, with Chris Nelson and DJ LeMahieu getting more time than usual. Tulowitzki's absence probably won't cost the Rockies a playoff spot, but if they finish a game or two out, we might remember this DL stint.