The Nats won last night. The Nats have the best record in the NL. The Nats are playing arguably their best baseball of the year.
Zimmerman went down yesterday.
In of itself this doesn't stop the Nats from taking the NL East. Assuming it's something bad (and it seems like everyone does) Rendon takes 3rd, Espy takes 2nd, and the Nats end up with their best defensive group on the field. The offense takes a hit but if the Nats can't compensate for having one guy out of the lineup then they don't deserve to take the division.
The problem is what it sets the Nats up for, which is a scenario where one more injury cripples the offense. It may not - 60 games left you could get a decent run from a McLouth or even a Frandsen (it's not impossible!) - but one more injury would likely leave the Nats with the dreaded "easy inning" where Espy/?/pitcher gives the opposing starter time to relax and regroup. The offense never really clicked before whenever two guys (or more) were out. I don't see a reason why it would now.
It would also, in my mind, demote Zimmerman to Ramos status when it comes to injury, which is "hope to get 100 games out of him". That's probably not fair, he's played at least 142 games four of the last 5 years, but it's how I feel. The every third year massive missed time due to injury has to catch up with a body, especially one a couple months from 30 years old who has spent the last year and a half dealing with an arm issue. Next year the Nats will have to plan around this. (Don't ask me how just now)
Do the Nats make a play for someone now? Headley would have been the obvious choice, excellent defense, history, recent play, and home/road splits suggest he's due to hit better (and that he can hit righties - which could allow the Nats to do a platoon of sorts with Espinosa). He's off the table now. With Luis Valbuena is crashing, the Nats are left with probably Martin Prado or Trevor Plouffe if they want guys that can play everyday. Both are better versus lefties.
My guess is that they don't make a play. Again - the Nats don't NEED to do something and Rizzo has shown a strong proclivity to ride the horses he brought to the dance (something like that) the past few years in that situation (hell, he's done it when they do need someone). So I don't see him making a move unless Zimm is out for the rest of the year.
Still, there's a chance it isn't too bad. Just keep repeating to yourself. 15-day DL. 15-Day DL. 15-Day DL.