Last year the Nats had amazing starting pitcher health. For example here are the number of missed starts (where a whole rotation turn took place without said pitcher) for the Nats starters last year:
Gio : 0
ZNN : 0
EJax : 0
Strasburg (while in rotation) : 0
Detwiler (while starter) : 0
Hmm that's not a lot is it?
While neither Strasburg or Detwiler got to their 30th start it's likely both would have if given different circumstances. How often does that happen, that 5 starters get to 30 starts a piece? Well since the 5 man rotation became the standard (let's say 1982 for the sake of argument - that's 30 years and that gets us past the strike year of '81) it's only happened 7 times. that's 7 times over like 800+ seasons, or like once every 3 years or so. It's a big recipe for success. None of these teams had a losing record and the last 6 averaged 95 wins.
Having four starters hit the 30 start mark is a lot more common (an additional 72 teams) but overall that's still not often. 79 times over 800+ seasons worth of teams is about 3 teams a year. And how many times has a team managed to do it in back to back seasons? I counted 8 times (and only twice in back to back to back years for what it's worth)
The Nats do have things going for them. The simple way of looking at it is the older you are, the more
pitches you throw, and how often you've been injured before matter
most in figuring if you are going to be injured this season. (Here's a recent article from BP about it) . The Nats primarily have young pitchers who either haven't really been injured (Gio) or haven't suffered any game skipping injuries since their major surgeries (Detwiler- hip, ZNN Stras - TJ). They haven't overly stressed any of their arms, keeping the # pitches out of the high end. But you have to think other teams probably had the same circumstances. As well as the Nats have set themselves up it isn't very likely the Nats will have this kind of health in 2013, and it's nearly impossible they will have it over the next two years.
Exactly how likely is a major injury? That's hard to say. A lot of stuff goes into injury risk and even then it's not hard and fast. To put down a number for the Nats would be just major speculation.To give you an idea though of how unlikely it is - let's say you think Haren has a 25% chance of having a major injury, and Detwiler, Strasburg, and ZNN have a 10% chance, and Gio 5%. That doesn't seem crazy does it, maybe a little skewed to the Nats even? Well given those numbers it's basically 50/50 the Nats make it through the season with none of these guys having a major injury. A coin flip.
I would say this - it's pretty likely that the Nats will suffer a major starting pitching injury next year. I'd say Haren is the most likely (obviously), followed by ZNN (shoulder issues last year), then probably Detwiler (I worry about the hip more than TJ), then either Gio or Stras depending on whether you care more about pitches (Gio) or the TJ (Strasburg). But we went over this in the Gio "suspension" article, something like that alone isn't going to derail the Nats season. What they need to avoid is the scenario where 2 or more arms go down for major time. That isn't very likely (with the completely made up numbers above - I figure the chances are around 15% and nearly all that is the "2" scenario, 3 or more is less than 2% of the time), but it happens to a few teams every year.
While the Nats have set themselves up pretty well for it NOT to be them the move from Haren (32 with recent injury issues) from Jackson (29 and one of baseball's most dependable arms) does increase the likelihood. It's up to the baseball gods now.