VIERA, Fla. — Jon Niese was more inclined to discuss details than the fact he put zeroes on the scoreboard yesterday during his spring debut.
Three shutout innings, fine. Two walks issued to the Nationals with two outs? Not fine.
“Obviously, there are more things to work on,” Niese said after the Mets’ 5-3 loss to the Nationals. “You can’t issue two-out walks.”
He was referring to walks Jayson Werth and Ivan Rodriguez received in the first and second innings, respectively. Otherwise, the Nationals managed just two singles against the 24-year-old lefty. Niese struck out two and threw 36 pitches over the three innings.
Unlike last spring, when he had to beat out Fernando Nieve, among others, for the final spot in the rotation, Niese doesn’t have to win a job this year. He earned that right by going 9-10 with a 4.20 ERA for the Mets in 2010, despite a late-season collapse in which he lost five of his last six decisions.
If there is a theme manager Terry Collins and pitching coach Dan Warthen have preached to Niese this spring, it’s the season is a marathon.
“He’s gone through one full season, and he knows now what it takes to get through the season,” Collins said. “At the end he got tired, got a little fatigued. You get in the middle of the season, you might want to back off some stuff. It might be in the running program, shorter bullpen, shorter sides, so you still have something left in September.”
Collins said the fact Niese had success last season should allow him to take a more measured approach to his work.
“When you’re a young player like he was last year, it’s an all-out effort every day because you have something to prove,” Collins said. “I think now he realizes, ‘I can cut back on certain parts of the program.’ And we’ll be involved in that.”
Though Collins hasn’t announced his rotation officially, beyond Mike Pelfrey starting opening night at Florida, it is likely Niese would be second and R.A. Dickey third, splitting up the right-handers.
Dickey is scheduled to make his spring training debut today against the Cardinals, and will have followed Pelfrey and Niese in succession.
Niese, who struggled with control during his August and September skid last season, is determined to throw more strikes this spring.
“It’s just one of those things where you want to throw a strike and you don’t, but it’s something I’m going to work on,” Niese said. “The focus has to be there, and just eliminate the walks.”
Warthen said maturity, more than guidelines set by the coaching staff, will allow Niese to be strong for a full season.
“He’ll do it on his own, just shortening his bullpens, feeling fresh, cutting his pitches between starts,” Warthen said. “He knows he needs to stay in good physical shape throughout the year. He’s always had a good work ethic, so he’ll continue to just get stronger.
“[Last year] was the first time he’s gone a six-month season, truly. In September he was maybe worn out, and that happens to a lot of first-year pitchers.”
mpuma@nypost.com