PHOENIX -- Colorado rookie third baseman Jeff Baker hasn't approached his surprise Major League stint as a temporary assignment. Nor has he approached it as the finals of "Amateur Night at the Apollo," some kind of do-it-or-lose-it showdown.

Baker, 23, has started five of the Rockies' first six games after being pulled up from Double-A Tulsa on the eve of Opening Day, after projected rookie starter Garrett Atkins went on the disabled list with a hamstring injury.

Baker's results have a predictably bipolar look. He went 2-for-5 with a home run and a double on Opening Day, but is 1-for-14 since. That includes Monday's 0-for-4 performance in the 2-0 loss to Arizona. Defensively, he has committed one error, on a low throw. He isn't preoccupied with showing off his arm strength. He has made several above-average plays with the glove.

"If you're trying to do something to stay [in the Majors] once other people get healthy, I don't think that's going to be successful for me," Baker said. "For me, it's the same thing. It's just the same game again, at a higher level.

"I think I'm bringing everything I have every day. I'm not going to go back and say, 'If I get more comfortable up here down the road, I'm going to let it all hang out.' If the chance is there to make a great play, I'll make that. If not, I'll make the good play or the routine play."

Manager Clint Hurdle said Baker has "held his own as far as I'm concerned" before Monday's game. But by night's end, his batting average stood at .158. Whether that bears closer examination is anyone's guess. It's better than rookie catcher JD Closser's .143 and not as good as Matt Holliday's .222.

Veteran utilityman Desi Relaford has completed a rehab assignment for a knee injury and is about to be activated, possibly on Tuesday if he can get a flight out of blizzard-buried Denver.

Early speculation on who will lose his place centers on utilityman Alfredo Amezaga, who would have to clear waivers for the Rockies to keep him in the Minors. Amezaga had his moments as a late-inning glove man with the contending Angels during the previous three seasons, and fits better in that situation.

If that's the case, a decision on Baker most likely will not be made until Atkins returns. The Rockies are being careful with Atkins, so that decision isn't immediate.

"Two weeks from now, he might be way better than he is right now, he might not be as good as he is right now," Hurdle said. "But that's what we've got to weigh.

"It would be tough to lose Amezaga because he has some value, but we are in a position where it is tough to carry specialist-type people."

Whatever decision the Rockies make, expect them to ensure Baker of playing time. The Rockies have kicked around teaching Baker to play the outfield because the system is stocked at third, but once Atkins returns, the club will not hasten the outfield teaching and use Baker as a part-time player at third and the outfield.

"The development of Baker is an issue that we don't take lightly ... he needs to get at-bats," Hurdle said. "If he's not going to play here regularly, he needs to go play in the Minor Leagues. "It's not his time to be a bench player. He's a core player for us, we feel in this organization. He's a player we feel is going to make an impact on our future."

Tsao's back, Lopez is leaving: Right-handed closer Chin-hui Tsao rejoined the team on Monday, after completing his rehab from a sore rotator cuff by hitting 94 mph with a fastball during a 1-2-3 inning for Class A Modesto on Sunday.

Hurdle announced that the Rockies optioned left-hander Javier Lopez (seven hits, five runs in two innings) to Triple-A Colorado Springs, but he might not make it. Lopez, Hurdle and general manager Dan O'Dowd will talk on Tuesday.

Hurdle indicated the Rockies would be hoping to trade Lopez to a club in need of a left-handed specialist, something the Rockies prefer not to have because of the load the bullpen carries in general.

On the Rox: Relaford will undergo strength tests before being activated. It could have happened Monday, but with the difficulty getting a flight to Phoenix, Hurdle said, "It's a long walk. Dan [O'Dowd] was supposed to come with him." ... Going into Monday night, Colorado's eight active rookies combined to hit .304 (21-for-69) with 11 runs, three home runs and 10 RBIs. Two rookie relievers, Ryan Speier and Marcos Carvajal, were a combined 1-0 with a 1.59 ERA. The Rockies led the Majors in man-games played by rookies (792) and used a National League-leading 18 different rookies last season. Only Kansas City (21) used more.

On deck: After a wild and often rough 2004 as Colorado's closer, right-hander Shawn Chacon returns to a starting role on Tuesday night against the Diamondbacks at Bank One Ballpark.