"Oakland's injuries come, wave after wave, in increasingly distinct groupings.

One year, there were a lot of back problems and various broken bones. One year, it seemed to be hips. Oblique strains were ubiquitous for a time.

This year, it's elbows. The team's projected No. 1 starter, Justin Duchscherer, had arthroscopic elbow surgery in March. Closer Joey Devine had elbow-ligament-replacement surgery in April.

In May, reliever Dan Giese went on the disabled list with an elbow problem, and he, too, needed Tommy John surgery. This week, promising left-hander Josh Outman's season was ended by the same procedure. Pitching prospect Michael Ynoa was shelved last month with a sore elbow, though he might be allowed to resume throwing soon.

What is going on? These aren't insignificant injuries. Tommy John surgery takes 12-18 months of recovery time, so Devine won't be back until next spring, Giese potentially the middle of next season, and Outman late next season or perhaps even 2011.

Are the A's not doing enough to prevent these injuries? Are they drafting or acquiring pitchers whose mechanics make them more prone to elbow injuries? Are pitchers being overused, or are they throwing too many sliders, a pitch thought to be harder on the elbow than most?

"The guy who can come up with something to prevent those Tommy John surgeries will be a very, very rich man," Oakland general manager Billy Beane said, "because they just seem to come with use and there's no predicting when they're going to happen."

Some pitchers, like Devine, have come to the A's with past elbow issues. Duchscherer has had several other injuries, and it's possible that previous hip problems altered his delivery enough to put more stress on the elbow. Duchscherer had a bone spur removed and he might have been pitching for the A's by now were it not for recurring back trouble.

Many elbow problems come without warning. Giese and Outman had not had previous elbow discomfort and Andrew Bailey, the A's closer, said his elbow didn't even hurt when the ligament tore in 2001.

"It just felt like water was dripping down my arm onto the field," he said. "They told me later it was the blood dripping down inside my arm after I blew my elbow out. I was looking down to see if it was sweat."

Many scouts say they have an idea of pitchers who might wind up with elbow problems. Relievers who get a lot of use are candidates, especially those who throw almost exclusively sliders, a la Kiko Calero, whose elbow blew out after a heavy workload in Oakland. Yet relievers can get away with more than starters sometimes because they throw fewer innings.

"You certainly see a lot more bad arm action and deliveries in the bullpen," one scout said.

Scouts look for pitchers with deliveries that appear to put excessive strain on the elbow. Anything that looks awkward, anything in which the elbow is lagging behind, those are giveaways. Low three-qu