...Why?

So something I just cannot comprehend is Trevor Cahill's abandonment of his curveball. It was totally hyped as his strikeout pitch last year, you always read about his awesome sinker and punchout knuckle curve. But wait, whenever I've watched Cahill this year, I can never remember him throwing a curveball. Like, ever. So I got to looking at some pitchf/x data over on fangraphs, mostly because it's fun and looks cool, but something just kind of caught me:



That would be Cahill's first start in the bigs (4/7). He was supposed to have used his curve quite a bit in the minors, I count three here. In his first start! I see 3 curves, 6 or 7 sliders. By his 4th start, he wasn't throwing breaking balls at all. Seriously, look:


So it seems like he wasn't feeling the curve even before this year, he barely threw it in his opener, and scrapped it completely shortly after. He now throws the slider semi-frequently, but it really isn't that good of a pitch. So I'm wondering, is it a confidence thing? Does it just not feel good to throw a slow loopy thing up there when even your hard stuff is getting hammered? Something kind of interesting, but maybe (probably) completely random and unrelated:






First graph is movement chart for Rick Porcello's first big league start (4/9), and the second is from the most recent start fangraphs has got (9/13). He threw some sweet bendys back in April, but look at that recent graph! Either his stuff has disintegrated (I'll bet he's tired?), or he too has scrapped the curve for a slider. WHY?! Again all I can think of is confidence, but it just seems so counter productive to totally scrap a pitch that has worked for you in the past. Do some coaches just have some bias against rookie curveballs? Do scouts just fall so head over heels with someones fastball that their praise gushes over to the shit secondary offerings? I really don't understand it.

Cahill has had some ("some" is generous actually, more like a few crumbs of) success this year, and to be honest, his fastball change combo seems to have so much potential that his breaking stuff probably doesn't have to be that great for him to be a useful pitcher. I just don't understand the lack of curveball action at any point this season, when it was hyped as a quality pitch not just a year ago.