ATLANTA – Kennys Vargas, his big grin and bigger bat were in the Twins lineup Wednesday against the Braves. It was a result of Joe Mauer needing a day off because of sore quadriceps.

That's how Vargas has been getting into the lineup lately, when someone needs a break.

It's not the best way for Vargas to prove he has major league ability. The 6-5, 290-pound switch hitter from Puerto Rico has the most power of anyone on the club not named Miguel Sano. But with Mauer at first and many options for designated hitter, Vargas will be challenged to keep a sharp bat.

Wednesday, he was in the starting lineup for only sixth time in 16 games this month and the second time in six days.

"It's hard," Vargas said. "It's something that I'm not used to. It's something that I haven't done in my career. For example, today I'm in the lineup but I haven't played in a few days. It's hard to be on the bench and see the pitchers who throw fast and it's hard to adjust to. But you have to do it. It's my job and I have to do it."

Still only 26, Vargas teases with his power potential but can create frustration with strikeouts and poor footwork at first base. He was called up July 4 and was named AL player of the week for batting .471 with three homers and five doubles over his first six games. He has slowly cooled down since then, entering Wednesday batting .272 with six home runs and 13 RBI in 24 games played. But his walk rate, which was 5.1 percent in 2014 and 4.9 last season, is 16.3 percent this season. That shows he's making adjustments.

"It's part of the process," he said. "You come in the first year and you start learning and now this being my third [year] up you learn what the strike zone is here and you start adjusting to it."

Vargas' long-term future with the Twins is uncertain. He made the Opening Day roster last season but was sent down May 19. The team gave him another chance in June, and he was gone roughly two weeks later, dropped all the way down to Class AA Chattanooga. He did work his way back to Rochester and returned to the Twins in September.

But the club signed Byung Ho Park to a four-year, $12 million deal in December. After a fast start, Park fizzled and was sent to Rochester on July 1. But Park is under contract for three more years, and he looms as a threat to Vargas' chances to stick with the Twins.

Twins manager Paul Molitor even called Vargas a "peripheral player" on Wednesday.

"I think the jury is still out a little bit," Molitor said. "I think he shows you signs of maybe potentially evolving into a guy you could put out there as a DH or some first base. We see a lot of players through the years where they have power and it plays from time to time. And there's questions is if you give them 500 at-bats for five years in a row, how many home runs would they hit.

"He kind of falls into that mold, a guy you kind of wonder about. You don't know how it is going to fit around here if we're going to have the opportunity for him to play that much until something unforeseen happens."

Vargas, signed as an undrafted free agent in 2009, has already gone from weighing nearly 300 pounds and showing few skills to reaching the major leagues. So he is used to fighting the odds.

"It doesn't matter if you are a first rounder, bonus guy or free agent," he said. "I try make the best of my opportunity, and here I am. You have to show that you belong."