“If he was playing every day and got into a groove with that big, heavy bat, he could use it and have no problem with it,” DeRosa said. “I didn’t think it was the right way to go coming off the bench.”

On Saturday, Bernadina walked up to DeRosa, patted him on the shoulder and said, only half-kidding, “This is the guy who changed my life.” Since Bernadina switched from a 34-ounce bat to a model that weighs 31 ½ ounces at DeRosa’s insistence, Bernadina, 28, has hit better and more consistently than at any point in his career.

In 103 plate appearances since the Boston bat swap, Bernadina is 30 for 90 with 12 walks, good for a .333/.412/.389 slash line. Bernadina deserves credit for his performance, but the assist goes to DeRosa.

“He’s so strong and so muscley, all he’s got to do is get his hands to the ball and he’s going to drive it,” DeRosa said. “I didn’t feel like he needed to use such a heavy bat. And when he’s hitting once every four or five days, carrying an axe up there with you, I just feel like you’re doing yourself a disservice. You got to be able to have a bat you can manipulate and get to everything. He got hot with it. He’s played great.”

Manager Davey Johnson said Bernadina made solid adjustments in spring training, shortening his swing and eliminating a slight uppercut. Once the season began, Bernadina’s swing got bigger as he received infrequent playing time. Moving to a lighter bat allowed him to regain the feel he had in spring.

“You control it more,” Bernadina said. “Since then, I’ve been feeling good at the plate.”

Bernadina said he has also improved his focus. Bernadina is a happy, laid-back guy, well-liked in the Nationals’ clubhouse. He also has as much raw athletic ability as anybody in there. He has perplexed scouts who see his potential in flashes and then stretches of mediocrity. The Nationals have been reluctant to part with Bernadina because of his high ceiling, and this year he is getting closer to it.

“Just watching him, you see so much potential and so much talent,” DeRosa said. “Roger’s got all the tools in the world to be an everyday starting center fielder. I just think it’s, a lot people say, ‘What does it take to be an everyday guy?’ You got to be consistent. You got to be every day for 162, that type of player. You can’t just take time off. You got to keep going.”

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