ST. LOUIS -- Defense has played a key role in the Rays' move to the top of the American League East. And a big part of that defense has been the work of the keystone combo composed of shortstop Jason Bartlett and second baseman Akinori Iwamura.

Currently, the Rays have 46 double plays on their ledger, which is 10 more than their opponents.

"They've happened at the right time, no question," Rays manager Joe Maddon said.

A shotgun wedding put Bartlett and Iwamura together, Bartlett arriving from Minnesota in a trade and Iwamura moving from third to second to accommodate the arrival of rookie third baseman Evan Longoria. But the chemistry between the two has been just short of incredible.

"Honest, I did not expect Aki to be this accomplished this quick, I did not," Maddon said. "So that has really been pleasant to see, and again it goes back to Spring Training. He and J.B. were just hanging out together all the time. I think it's carried over into the season. They've made nothing but big double plays when they've mattered."

Iwamura returned to Japan in the offseason to work with a former coach on the position change, while Bartlett bought into his new partner and rolled with the punches. The low-key Bartlett, who stabilized the Rays' shortstop situation by bringing range and consistency to the position, said he hasn't been surprised by Iwamura's stellar play.

"I said from Day 1 that Aki was fine over there," Bartlett said. "I didn't see any flaws that first day. I knew from then on it wasn't going to be that hard to get to know him.

"You've got to give him a lot of credit. He's worked hard at it. A lot of guys who switch to the position are kind of like robots over there. ... He's done so many reps that everything is just coming natural to him. I said at third, he was probably one of the best [players] over there last year, so I didn't see any reason, with his athletic ability, that it was going to be hard for him."

While Iwamura did all the drills imaginable heading into the season, there have been other facets of playing the position that could not be simulated, leaving live-game action as the setting for Iwamura to make his bones.

"There are a lot of little nuances you can work on," Maddon said. "You can talk about it in advance, but it ends up being like a quarterback in football. You just have to see the target and not the rushing linemen. And a guy moving to second base who hasn't done this before, it's kind of upsetting because you can hear the guy coming at you, and he's done a great job."

Iwamura called every day a learning process.

"It could be the same thing at third, but avoiding hard slides at second is new, and every day there is something different -- a guy sliding a different way and I have to avoid that to make different throws from different angles," Iwamura said. "But I feel comfortable out there."

Rays pitchers, almost to the man, have expressed their confidence in the pair, while the rest of the club's defense has noticed the pair's work as well.

"They're turning it, man, at crucial times, too, being real quick," outfielder Carl Crawford said. "It looks good from the outfield. I just hope they can keep it up."