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8/10/2013 9:20 P.M. ET

Mets won't use Wheeler out of 'pen in September

PHOENIX -- Though the Mets will continue to monitor Zack Wheeler's workload down the stretch, they will not use him as a relief pitcher to curtail his innings.

Manager Terry Collins originally floated the idea of using Wheeler out of the bullpen late last month, reasoning that the team's six-man rotation may not do enough to limit his workload. Wheeler finished last season with 149 innings split between two levels, and Collins said Saturday that he should end this year in the 180-190 range.

Entering Saturday's play, that gave him approximately 60 innings to work with over eight starts -- an average of more than seven per outing, which -- assuming the Mets stick with a six-man rotation -- should be enough to last Wheeler through September.

"We've still got him for a number of starts," Collins said.

The same may not be true of Matt Harvey, who is already within 10 innings of matching the 169 1/3 he threw last year. Harvey will be allowed to hit 200 innings this year, but likely not much more than that, meaning the Mets could still shut him down in September. The team is using a six-man rotation largely to avoid that situation for as long as possible.

Aggressiveness has Mets as top baserunning club

PHOENIX -- Pitching, defense and hitting are all critical to winning. But Mets manager Terry Collins knows there is another reason why the Mets have been playing significantly better since late June.

"Look at the numbers," Collins said. "We lead all of baseball in taking extra bases."

The most relevant statistic is a metric called Ultimate Baserunning Rating (UBR), which attempts to quantify baserunning contributions in the same way that Ultimate Zone Rating provides rough estimations of defensive value. The Mets lead the Majors in that category by an enormous margin, entering Saturday's play with a 15.5 UBR, according to Fangraphs.com. That indicates that New York's baserunning has been worth 15 runs more than an average team's.

The next closest club, the Royals, had an 8.7 UBR. Fifteen of the league's 30 teams had a negative UBR, indicating that they have cost themselves runs on the bases.

Particularly valuable to the Mets have been David Wright, Eric Young Jr. and Daniel Murphy, each of them at least three runs above average.

"I attribute that to the fact that my third-base coach is extremely aggressive," Collins said. "He forces people to make plays, forces other teams to make plays. We've scored a lot of extra runs, which has kept us in games and helped us win games."

The downside of such aggression can be significant, simply because it is more noticeable than the upside. Third-base coach Tim Teufel took heat after Friday's game for encouraging Marlon Byrd to pursue an inside-the-park home run with no outs in the second inning, resulting in a critical out in a one-run loss. But Teufel rarely receives credit for all the runs he has helped create this season.

"Some days it's going to work and some days it's not," Teufel said. "I think so far this year, it's worked more than it hasn't."

Teufel believes the Mets have gained a reputation for taking extra bases, which forces opposing defenders to work quickly and fall victim to more mistakes -- a bonus made possible through nothing more than sheer aggressiveness.

"We can control that," Murphy said. "We can't control hits or errors a lot of times, but we can always have effort on the bases."

Niese set to return, hopes to finish season strong

PHOENIX -- Before Matt Harvey broke out this summer to become the Mets' ace, Jon Niese served as the team's Opening Day starter.

For Niese, Sunday might as well be Opening Day No. 2. The left-hander will return from the disabled list to start his club's series finale against the D-backs, kicking off what he hopes will be a strong run to finish this season.

"I think it's important for Jon Niese mentally to know that his arm's OK," manager Terry Collins said. "So if he finishes strong, he knows he'll be fine with the rest over the winter time, and he'll come into Spring Training ready to go."

On the disabled list since June 21 with a partial tear of his left rotator cuff, Niese has since admitted to pitching through discomfort for weeks before that date. He does not regret it -- Niese believes his rotator cuff would have torn regardless of whether he pitched through pain. But he was not sure he would be able to make it back this soon.

"It actually ran a lot smoother than I thought it was going to," said Niese, who will be limited to around 95 pitches Sunday. "When the doctor tells you that you have a tear, it's kind of scary. You don't think that you're going to be back in the time that you hope for. Luckily, it went smooth and I was able to get back at a pretty rapid pace."

To make room for Niese, the Mets will option a position player to the Minors, returning to a six-man rotation and a four-man bench. The obvious candidates are outfielders Andrew Brown and Mike Baxter, with Brown perhaps more at risk because Baxter is the only left-handed bat on the bench.

Worth noting

Two scoring changes to the Mets' Sunday loss to the Royals have resulted in an extra earned run on Wheeler's permanent record. Major League Baseball officially changed Daniel Murphy's error in the second inning to a single for Lorenzo Cain, and Marlon Byrd's error in the fifth to a double for Alex Gordon.

Anthony DiComo is a reporter for MLB.com. Follow him on Twitter @AnthonyDicomo. This story was not subject to the approval of Major League Baseball or its clubs.