ARLINGTON -- On his first off day as a member of the Rangers, Jonathan Lucroy sat down in Houston for a relaxing afternoon of ... scouting reports. Headphones on, legs shaking restlessly, head bobbing, he sat there for two hours going over the pitchers he'd just caught and those he would catch.

It's just what he does.

What the Rangers have discovered about Lucroy in a little more than two weeks since he joined the team is that the guy is relentless in his preparation, looking for every little way he can to help his pitchers.

"You'd be hard pressed to think anybody prepares in the same way this guy does," Rangers manager Jeff Banister said. "If you want to be great at your craft, there is a price to pay for it. He puts in the work. That type of work gains respect immediately. From what I'd heard and what I'd asked people about him, I knew he was serious about preparation, but I didn't know that it was this extensive. He's off the charts."

And he's good at. Just consider what he's done for Yu Darvish. He's fixed Darvish's run-support problem, virtually all by himself. On Wednesday, he drove in three runs with a game-tying homer and an opposite-field double in the Rangers' 6-2, sweep-clinching win over Oakland.

He came in, worked with Darvish one game and saw the club score nothing for him in six innings. That was the fifth start in a stretch in which the team managed all of six runs while Darvish was in the game. So Lucroy went to work. In his last three starts with Darvish, he's 7 for 14 with three homers and nine RBIs; the Rangers have averaged more than five runs while Darvish was in the game, and they've won all three.

OK, OK. Maybe -- maybe -- the offense is a little bit coincidental, but the truth is, by any measure, he's had an enormous impact on the staff. Start with the simplest metric: The Rangers are 8-4 with him behind the plate. A bit more advanced: The staff ERA is 2.92 with Lucroy behind the plate; it is 4.43 with any other catcher.

He's found a way to get Darvish to rely more on his two fastballs than on secondary stuff. He's found a way to get Martin Perez back to using his changeup regularly.

In short, he's gotten pitchers to rely on their best pitches, believe in them and use them.

"Simplification is the most important of the game for me," Lucroy said. "This is simple: Use your strengths as best as you can. I'm a big fan of the KISS method -- Keep It Simple, Stupid. There is no reason to fix something that isn't broken. Don't try to be too tricky. Just let your ability to do the work."

On Wednesday, it was more of the same with Darvish. Instead of relying on secondary pitches to trick hitters, Darvish used his two- and four-seam fastballs to set up at-bats. When the A's proved to be on the fastball early, Lucroy and Darvish were able to seamlessly transition to a more offspeed pitches to slow the bats down. Once that was done, he sped them back up.

Darvish's slider is exceptional, but so are his two- and four-seam fastballs and his cutter. He commands them. When he leads with them, the strikeouts go up and the walks come down. He finished with nine strikeouts Wednesday, finishing Max Muncy and Coco Crisp to end the seventh with runners on first and third. Crisp, who led off the game by homering on a 91 mph four-seamer, couldn't catch up to Darvish's 95 mph heater to end the inning. Darvish let out a huge yell and a Tiger Woods-like thrust with his fist.

"I think one of my strengths is that I'm able to make adjustments," Darvish said through a translator. "But, with Lucroy, we are always on the same page and it's easy to do it. That's what we did tonight. ... He works and studies so hard, it gives me so much confidence. There is an extreme trust that I feel out there."

The bat doesn't hurt either. Lucroy tied the game with a one-out homer off lefty Sean Manaea in the fourth. In the seventh, he broke the game open with a two-run, opposite-field double off Liam Hendriks.

"He has swung the bat well in [Darvish] starts," Banister said. "To get us on the board with the homer at a point when things looked pretty challenging against the left-hander, that was a big inning."

It helped Darvish.

And isn't that a catcher's No. 1 job?

Twitter: @Evan_P_Grant