NEW YORK -- A glance at Ramiro Pena's stature alone hardly inspires confidence in his big league abilities. He is not particularly tall, but he is particularly slight. He is the typical middle infielder of generations past, when litheness and finesse were more common than bulk.

Pena is here for defense, and his team didn't expect him to be here all that long. But in recent days, he has raised Yankees eyebrows with the type of at-bats that help unproven players stick on big league clubs.

The results weren't quite there until Thursday night, when Pena lined a two-run double into the right-field corner to give the Yankees some much-needed insurance in a one-run game.

Grinning after the game, Pena accommodated two waves of interview requests before calling it a night.

"He's enjoying himself," shortstop Derek Jeter said. "You can genuinely tell he's pretty excited to be here. He's got a smile on his face all the time. He's working hard. It's probably a different role for him, but he's putting his work in as well. He's gotten the opportunity and he's contributing."

Pena is contributing more than anyone expected from someone who never ranked even close to the top prospects in the team's system. Pena never batted higher than .280 in the Minors, nor slugged better than .357. His offensive skills seemed as slight as his build. Yet dropped into more playing time once Cody Ransom began to struggle, Pena has earned a reputation for fine at-bats.

Through 16 games, he has seen an average of 3.97 pitches per at-bat, more than regulars Jorge Posada, Melky Cabrera and Robinson Cano, and on par with the team's overall average of 3.98.

Certainly the Yankees would be thrilled with any small offensive contributions they receive from Pena, who is becoming more relaxed the more playing time he receives.

"This is good to be in the game," Pena said. "They put me on the roster and they put me in the lineup, and [I'm playing] every day. It's getting comfortable for me."

More important to the Yankees are Pena's skills at third base, a position he never played during four seasons in the Minors. A natural shortstop, Pena has not committed an error in 62 innings at third base this season.

It's all forced manager Joe Girardi to consider keeping Pena on the roster even after regular third baseman Alex Rodriguez returns later this month from right hip surgery. The decision, according to Girardi, will depend upon whether the team feels Pena will benefit more from playing every day in the Minors or from helping the big club defensively in the Bronx.

"That's a bridge that we'll have to cross sometime in the near future," Girardi said. "There will be a lot of discussion probably in the next couple of weeks before we have to make a decision, but he has played very well. And he has opened a lot of people's eyes."

Including his own.

"It's awesome," Pena said. "I'm enjoying every day, even if I don't play. It's unbelievable just to be here."