Tanner Roark will get the ball today for his 31st start of the season, and should he happen to work 7 2/3 or more innings, he'll top the 200-inning mark for the 2014 campaign, a milestone for many pitchers. Roark has posted a 2.85 ERA this season, which only ranks 17th among qualified major league starters. No big deal. He has an ERA-plus (which is adjusted to the pitcher's ballpark, where a league-average mark is 100) of 131, eighth-best in the National League. Decent, I guess. His left-on-base percentage is 79.8, eighth-best in the majors, which means he excels at working out of jams.

By many measures, Roark has had a stellar season, this after coming on to the scene last year in his rookie campaign and wowing talent evaluators and fans with his numbers, poise and bulldog-like mentality on the mound. But as we get closer and closer to the postseason, it's time to think about how Roark will factor into the Nationals roster for the NL Division Series. And despite how good Roark has been this season, it seems likely he won't hold a rotation spot for the NLDS. Roark's versatility has made him valuable in his pro career. He has proven that he can be a more-than-effective starting pitcher, as we've seen. But he also has shown that he can work out of the bullpen and be a force there, as well. Roark made nine relief appearances with the Nats last season, posting a 1.19 ERA in 22 2/3 innings. He posted a 0.926 WHIP, struck out 19 and walked seven. The right-hander could work multiple innings for the Nats out of the bullpen, or he could be used in a one-inning stint, where his fastball would probably play up from the 92-93 mph that we usually see during his starts. In a sense, Roark's versatility might come back to hurt him when it comes to his desire to pitch in the postseason rotation. Gio Gonzalez doesn't have experience working in relief. Roark does, and he's proven he can handle the job. On top of that, Gonzalez has really started to hit his stride over the last month, posting a 2.79 ERA in his last six starts. Opponents are hitting just .213 off the left-hander with a .594 OPS, he's walked just one batter over his last three outings, and he's gone at least six innings six starts in a row. By no means has Roark pitched poorly of late. In fact, he's got a 2.56 ERA over his last six starts, including seven scoreless innings in a division-clinching win over the Braves his last time out. If Roark doesn't earn a rotation spot in the NLDS, it'll be of no fault of his own. He's been tremendous this season, and has established himself as a legitimate tough major league starter. But the Nats have five of those right now, and they'll only need four in the rotation come the NLDS. And it looks like Roark will end up being the odd man out.