Yes, and no. I'm in favor of putting Chapman in the rotation, because if he's in and Leake's out, the rotation is better. But in fairness to Leake, the bolded part really isn't true IMHO. Comparing apples to apples, very few #5 starters will show up on that "eligible for the ERA title" list because the typical #5 guy doesn't pitch well enough to hold the job. Most teams don't have four rotation-worthy horses, much less five. Here's a good article about fifth starters from Hardball Times -- a few years old but some things don't change much:
http://www.hardballtimes.com/main/bl...ifth-nl-style/
When a team can get 180 innings of 1.5 WAR pitching out of its fifth-best guy, as the Reds did with Leake, it's not at a competitive disadvantage. Far from it, as long as we're not paying too much money for it. And that's without getting into the whole measuring-a-pitcher-by-his-ERA thing, which I'll set aside for now except to say that he comes off a little better (but only a little) with the advanced stats.
But nonetheless, I'm not arguing the point that he's the guy to bump out of the rotation if Chapman's going in.