Zimmerman could return tomorrow, Roark continuing to make a statement

In case you missed it yesterday, Ryan Zimmerman played his second straight game in left field for Single-A Potomac, going 2-for-4 and playing seven innings in left. He got three chances in the field and had the opportunity to get in some work as a baserunner and test out his legs, going first to third on a ball. He also got caught in a rundown between third and home and slid back into the bag head-first, which, of course, is the way that he fractured his thumb in the first place. Manager Matt Williams relayed this information to reporters yesterday with a look on his face that said, "Please, Ryan, don't put our staff through that kind of stress again." The good news is that Zimmerman's thumb has passed every test so far, even the head-first slide. Zimmerman will play nine innings for Potomac tonight, and Nationals coaches and talent evaluators will be in attendance because of today's off-day. Should Zimmerman come through tonight's action OK, I would expect he'll be activated from the DL for tomorrow's series opener against the Phillies. The Nats keep slowly getting healthier. Now we'll see if it can start translating into some more wins. Switching gears a bit, it could certainly be argued that Tanner Roark has been the Nationals' most consistent starter over the first third of the season. Roark's 3.25 ERA ranks just behind Stephen Strasburg's (3.15) for the lead among Nats starters. Roark has eight quality starts in his 11 outings, has five starts where he's allowed one earned run or fewer, and his 1.13 WHIP is tops among Nats pitchers who have made at least five starts. The more I watch Roark pitch, the more impressed I am and the more I wonder how he kind of snuck up on everyone over the last couple of years. Roark was never really billed as a true major league prospect. He showed promise in the lower level of the Rangers system, including in the hitter-friendly California League, but had inflated numbers at Double-A Harrisburg in 2011 and lost 17 games at Triple-A Syracuse in 2012. That same guy is now taking the ball every fifth day for the Nationals, pounding the strike zone with his tailing two-seam fastball, working quickly and challenging hitters. He's enjoyable to watch because of his go-get-'em approach, and his teammates enjoy playing behind him. "I think over the last year-ish, he's showed us that he can throw strikes and he competes and can do a lot of things on the diamond," Williams said after Roark matched Yu Darvish for six innings yesterday, before allowing a single run in the seventh. "He handles the bat well, fields his position well. So all of those things combined show us that he's a rotation guy. Three pitches, really, for strikes. An occasional slider, occasional curveball, but fastball-changeup to both sides. "Today was a little off, a little command, but he made (pitches) when he had to make them. He pitched well." The Nats acquired Roark along with right-hander Ryan Tatusko (who has a 2.79 ERA in 12 starts at Syracuse this season) from Texas in exchange for Cristian Guzman at the trade deadline in 2010. Guzman ended up playing just 15 games for the Rangers, while the Nats are continuing to see the payoff in their end of the deal. Roark quietly goes about his business and won't say or do much to draw too much attention. His 92 mph fastballs won't wow you and his quiet, business-like demeanor might lead to him getting overlooked more often than not. But in his four months in the big leagues so far, Roark has shown he is more than capable of competing at this level.