Megdal: Jonathon Niese struggles with his nemeses, August and September

The big problem with Niese over the past two seasons has been durability as the season has worn on. So Tuesday night’s six-inning, four-run performance, just one start removed from getting knocked around by Arizona, is raising alarm bells. This is precisely the point in the past two seasons when Niese has worn down as well.

Through July 22, Niese had an E.R.A. of 3.59. In his three starts since, it is 5.21. Now, three starts are far from definitive. But consider his 2010 and 2011 seasons for context.

Through July 21, 2011, Niese had an E.R.A. of 3.73, with very similar peripherals to his 2012 season. He then posted a 6.82 E.R.A. over his next six starts, as the Mets gradually moved from not worrying about Niese’s fatigue to shutting him down at the end of August.

In 2010, a similar deterioration took hold. Through July 27, 2010, Niese had an E.R.A. of 3.43. He got knocked out in the fifth inning on August 1, part of a 5.45 E.R.A. over his final 12 starts. Even this doesn’t fully capture his late-season futility, since he rallied for a few good starts in August before a ghastly 7.57 E.R.A. over his final seven starts.

The problem with a pitcher who is only a stellar rotation member for his first 120 innings is obvious. For one thing, it means that any eventually contending Mets team would be unable to rely on him in August and September, let alone October, should the Mets make the playoffs.