ANAHEIM, CALIF. - Since they began their surge to the playoffs last August, the Twins and their fans have celebrated like Bryant McKinnie at a Pro Bowl.

They celebrated their belated excellence last summer, then their supposed last game in the Metrodome, and then a victory for the ages in their actual last regular-season game in the Metrodome.

They celebrated their front office's aggressiveness during a winter and spring that produced a trade for J.J. Hardy and contracts for Jim Thome, Orlando Hudson, Nick Blackburn, Denard Span and Joe Mauer. They celebrated their first glimpses of Target Field, and a roster as deep in position players as any Twins team since 1991.

All of the celebrating has obscured an obvious and pessimistic view of the roster: The Twins opened the 2010 season Monday night at Angel Stadium without a proven closer or ace.

Jon Rauch is a necessary gamble, given the price of trading for the only impressive closer currently on the market -- the Padres' Heath Bell. But Rauch is unlikely to keep the closer's job all season; the Twins will be lucky if he survives the month.

Scott Baker, the Twins' de facto ace, became the Opening Day starter by virtue of his service time in a Twins uniform. Then he pitched in the first inning like he didn't want Rauch to have to face a save situation in Game 1, throwing 31 pitches and allowing two runs.

Baker allowed a homer to light-hitting Jeff Mathis in the second, then retired nine in a row before the Angels and a pitch count in the 90s knocked him out in the fifth.

Baker pitched 4 2/3 innings, allowing five hits, three walks and four earned runs, in what became a 6-3 loss to the Angels.

Could Baker become an ace? "It's his turn," Twins pitching coach Rick Anderson said before the game. "He's been here, what, five years? It's his turn to start figuring it out. And it looks like, from most of last year and this spring training, he is starting to figure it out."

The absence of a closer will threaten the Twins every time they take a lead. Their absence of a true ace might not matter during the regular season, and Baker indicated last year that he will have a better chance of becoming an ace than Rauch has of becoming a closer.

Rauch failed miserably in his one opportunity to close games for a contender, for the Diamondbacks in 2008.

Baker has pitched well in stretches for a contending team. Last year, after recovering from an early- season injury, he went 13-3 with a 3.67 ERA from June 1 until the end of the season.

"I think he's starting to figure out his delivery more than he ever has," Anderson said. "He's making adjustments quicker."

Is there a chance of him staying on the mound this year, instead of engaging in walkabouts that made him resemble "Monk," the obsessive-compulsive detective?

"Yeah, it would drive you nuts," Anderson said. "He did it because he was searching for something."

If all five of their starting pitchers provide loads of quality innings, the Twins won't miss having a true ace until -- or unless -- they make the playoffs.

Their lack of a true closer is the more urgent problem, a problem that could cause an implosion of the entire bullpen.

At 6-11, with neck tattoos, Rauch looks like he might have finished second to Charlie Sheen for the "Wild Thing" role in "Major League."

"We've got the intimidating part down," Twins manager Ron Gardenhire said. "Now, whether he throws the ball the way he's capable of, we'll see."

A contending team doesn't necessarily need an ace and a closer, but one or the other would be nice.

Jim Souhan can be heard at 10-noon Sunday on AM-1500. His Twitter name is SouhanStrib. jsouhan@startribune.com