The Nationals' rotation will get yet another new look later this week, this one coming in light of the strained lower back that will send JD Martin to the disabled list on Sunday. In the short term, Martin's injury means Collin Balester will stay in the majors for a few more days, at least until the Nationals need another starter.
That will likely come on Friday against the Phillies, when Martin would have been scheduled to pitch next. The Nationals could bump it back to Saturday, pitching Ross Detwiler on regular rest. But they're using him on short rest tomorrow, so it seems likely they'd give him an extra day to make up for this week's workload.
From what I can see now, there's one reason the Nationals could have Detwiler pitch on the 30th: so they could bring Jordan Zimmermann back on the 31st against the Phillies. Zimmermann has a rehab start at Single-A Hagerstown on Monday, so he could make the start on regular rest. But the Nationals likely will want to wait until early August to bring Zimmermann back, giving him a little extra time in his Tommy John surgery rehab.
Scott Olsen? He pitched Thursday at Single-A Potomac, and would again need some schedule gymnastics to pitch on the 30th or 31st (he's currently lined up for the 27th). Jason Marquis pitched on Friday for Double-A Harrisburg, and is still likely a start or two away.
The other names to think about are the ones that came up this week before Detwiler was picked to replace the injured Luis Atilano. John Lannan is lined up to pitch Tuesday at Harrisburg, and Matt Chico is slated for Wednesday at Triple-A Syracuse. But in either case, the Nationals could have one of the two pitchers take Livan Hernandez's start on the 28th and they could bump everyone back a day. Or, they could put Hernandez in on the 30th and give him two extra days of rest - which is a possibility, given manager Jim Riggleman's intimations after Saturday's game that he might use Hernandez out of the bullpen for a few days. If that happened, Hernandez could get in some relief work at some point in what would be an eight-day layoff between starts and pick up on the 30th - or even the 31st, without a problem.
Those are all the contingencies I see at this point. But it is July, and the Nationals do have a long slate of pitchers waiting to come off the DL, so this could all look different by next weekend.