NEW YORK -- In rookie center fielder Kirk Nieuwenhuis, Mets manager Terry Collins knows what he sees one minute may not be what he sees the next.
Catch Nieuwenhuis two hours before the game, and the rookie may appear calm as can be. But when the game rolls around, his outlook changes.
"He's a football player," Collins said before Saturday's game. "He's got a football background. Those guys, when it comes to game time, they can change their attitude, they can change their makeup."
Nieuwenhuis, a high school standout in football in Colorado, first caught Collins' eye when the Mets' manager was the Minor League field coordinator. On Collins' first trip, he went to Binghamton, home of the Mets' Double-A team, where he saw Nieuwenhuis and Mets outfielder Lucas Duda during batting practice.
"I watched those guys -- there was a group of them -- during batting practice, and they were nice and loose and having a good time," Collins said. "I walked out on the field right before gametime, and they were different people. When the game starts, it's all business, and I really like that about Kirk."
Collins also no doubt enjoys Nieuwenhuis' bat. Since settling in to replace the injured Andres Torres, Nieuwenhuis has hit .371 with a .450 on-base percentage. He also has two home runs, including Friday night's opposite-field blast to left.
As long as Nieuwenhuis keeps getting on base, Collins says, he'll continue to consider using the rookie in the leadoff spot. At 6-foot-3 and 215 pounds, Nieuwenhuis doesn't fit the standard mold of a leadoff hitter. But that's the role he filled Saturday for the second time this season, in part to help break up left-handed batters in the Mets' lineup, but in part because of his on-base ability.