There are quite a few things at play here, many of which are mind boggling to me, but they are...
- Scott Boras is a big part of this decision. If he wasn't pushing so hard for it, I seriously doubt Rizzo would've went through with this exact plan (and instead would've opted for some other variation allowing his best pitcher to pitch down the stretch and in the playoffs).
- Rizzo doesn't want to mess with Boras because they have a (relatively) good relationship as Boras represents Strasburg, Harper, and Werth as well as a few of their top prospects. Other GMs have even joked that Boras is "co-GM" of the Nationals.
- Boras and Strasburg both were apparently dead set on him getting starts every 5th game (on normal rest) saying that his 'routine' (even extending to what he does between starts) was more important than taking opportunities to push him back or delay his starts.
- If Strasburg wasn't on board with this, he would be raising hell telling everyone (including Boras) that this isn't what he wants. If Chris Sale/his agent could go to KW and the Sox and overturn that decision, you bet Strasburg could do the same. Although Strasburg has said all of the right things publically (like "I'm going to fight this" just this past weekend), he obviously isn't fighting it very hard.
There are probably some things I missed, but this decision is out of this world stupid. Things in baseball are so fickle from year-to-year and the Nationals - with Strasburg - are quite possibly the best team in baseball. Taking their ace out of that formula, I'm not so sure and there's absolutely no guarantee that they'll be back at the top like they are now. Yes, they absolutely could be (and probably are) building something like the Braves of the '90s, but in this sport there are no guarantees (including the continued health of his new labrum).