I've been defending Manny for several weeks now, but this move needed to happen-- especially considering that the fifth starter can be skipped for a few turns, giving Manny a little time to stay on schedule and work on his stuff.
Parra only threw 55 pitches yesterday, so there's not much there to see if he tried changing anything with his pitch selection. He threw 7 curves-- a pitch I think he should throw more often, as that's his usual rate of throwing that pitch. It does look like he tried to throw more sliders.
Yesterday, Manny's velocity was up compared to his season average, but overall he's been down a bit this year. That's not a good sign, of course. His fastball has been about as effective as in the past, so I wouldn't conclude that the slight decline in velocity is related to his struggles very much.
I'm not really sure what exactly is wrong with Parra at this point. Hopefully he'll find something in his mechanics at AAA that will allow him to regain command and become more efficient with better control.
But before I let this go, I will emphasize the two things that are not wrong with Manny Parra: his stuff is just as nasty as always, and he's not ridiculously more hittable. His swinging strike rate is right at 9%, right where it was last year, and his K rate is about the same. And yes, he has gotten terribly unlucky. I think most of us realize that Manny does not "deserve" a 7.52 ERA right now. He deserves something closer to his 5.11 FIP or his 4.4 tERA. The last two years Manny stranded 70% of runners on base, around the league average, and this year it's suddenly 60%. The other factor is that pitchers don't have much control over BABIP (as we already know, though hitters do to some extent), and Parra's is .368-- way above anything that can be attributed to skill and into the range of bad luck.
Parra hasn't been performing to anyone's expectations and his control has been very bad. But we shouldn't evaluate him as a 7.50 ERA pitcher-- let's look at him as a 5.00 or so ERA guy so far, to keep it in perspective. I fully expect him to be back in the bigs soon, and even if he changes absolutely nothing, he should be far more effective. If he does find his control again, we'll have our good old 4.20 ERA Manny back again.