Bullpen Report: September 18, 2013

• The Rangers are certainly not playing their best baseball, and Joe Nathan didn’t help tonight. Texas’ closer was tagged with a “BS” in the box score after giving up a walk, a stolen base, and a single. Nathan has been steadily outperforming his peripherals all year, posting a mid-1.00’s ERA even with an xFIP north of 3.00. While that’s not a major concern, the fact that his BB% has spiked to 13.7% after the all-star break (and a walk began his undoing tonight) is somewhat concerning. His velocity has trended up later in the season, although he remains below his 2012 mark. The control bears watching (given some of Jeff Zimmerman’s work which implies loss of command is a potential sign of injury) and the fact that Nathan will be entering his age 39 season next year makes him somewhat of an low-upside keeper stash. That said, ride him for the next 10 days.

• One of the surprises of the year, the Royals bullpen (as a group) are putting up one of the top five relief seasons (by ERA) in the last two decades. A huge part of that success is Luke Hochevar, baseball’s third best reliever over the last 30 days. The righty has a 2.97 xFIP on the season, but has really turned up the wick over the last month, posting a ridiculous 48% K%.

The former top-flight prospect has always been stingy with the walks, but the move to the bullpen has resulted in a three mile per hour surge in fastball velocity and an almost doubling of his SwStr% (now sitting at an elite 13.2%). The velocity spike has turned his four-seamer from a -1.09 wFB/100 to a 2.48 mark, and allowed him to be an effective reliever throwing hard stuff (fastball/cutter) roughly 80% of the time.

Unfortunately, Hochevar is sitting in a pen full of big arms (Greg Holland, Tim Collins, Kelvin Herrera) so his value in standard leagues is stunted. However, assuming he doesn’t grab the ninth inning next season, he might make for a sexy late round pick to rack up peripherals. If he can sustain some of his late-season gains this year, he could flirt with 100 whiffs out of the pen next year. And that’s plenty valuable.

• Quick hits: Grant Balfour blew his third save of the season. His velocity looks OK and his rate stats aren’t too bad, but he’s been “eh” at best over the last month or so. His leash might get short in the playoffs if he has a couple more shaky outings. Mark Melancon showed he’s human today, coughing up a lead against the Padres (the Padres!?). As one of baseball’s top relievers by SIERA, I’m not concerned, but the Pirates could have used the win. Mariano Rivera worked around a couple hits in a multi-inning save (his 44th). Try and catch a couple of his outings over the last couple weeks as his days are winding down.

Closer Grid:

[Green light, yellow light, red light: the colors represent the volatility of the bullpen order.]