"Shrug off Aaron Cook's Opening Day struggle in Arizona. It was, after all, Opening Day, and the ball was carrying at Chase Field, as even the Diamondbacks could attest.

Last Sunday against Philadelphia, Cook may not have been Cook at his best, but on a frigid afternoon at Coors Field he was good enough to get a victory if the Rockies late-inning relievers hadn't been so bad.

Saturday, against the Dodgers?

There's no way to rationalize the mess.

The only thing keeping it from being a perfect afternoon was Cook, himself.

"Los Angeles in the day time?'' said Cook. "It's warm, You get a good sweat. You get good movement. It was as normal as it can get.''

That is, it was as normal as it can get, except for the results.

For the second time in three starts, Cook's sinker was missing. The Dodgers made him pay for it in a 9-5 Rockies loss in which only three of the 12 outs that Cook registered came on ground balls.

Heck, Cook even felt good.

"I wish I could put the blame on that, but physically, this is the best I have felt in a long time,'' he said.

And that, he said, is a concern for Cook in particular, and the Rockies in general.

Cook is considered their ace, but he's been trumped in all three starts so far this season.

And it is a puzzle. It's one thing to not command pitches and not throw strikes. But to leave pitches up in the zone? That's not Cook.

"It's why this game makes you scratch your head sometimes,'' said pitching coach Bob Apodaca. "sometimes things you take for granted turn out to be things you can't control. We've got to sit down and determine the problem.''

The numbers say there are plenty of problems.

Manny Ramirez hit two home runs off him on Saturday, and then Andre Ethier unloaded a three-run shot off Cook that made the score 5-0. Strange? Well, it is only the fifth time in Cooks career he has allowed three home runs in a game. And Ramirez is only the third player to hit two home runs in a game off Cook, the first to do it on the road.

Troy Glaus got him twice with St. Louis at Coors Field on Sept. 11, 2005, and on June 11, 2006, Matt Kemp of the Dodgers connected twice at Coors Field.

"His priority every time out is to establish the sinker,'' said manager Clint Hurdle. "That's No. 1 on his list. That did not happen (Saturday) and there was no Plan 2 or Plan 3.''

There doesn't normally need to be."