Derek Zumsteg, Author of the Book Cheaters Guide to Baseball, thinks he caught Angels Closer Francisco Rodriguez doctoring the ball on Opening Day, then today.

View the evidence for yourself

Francisco Rodriguez doctoring the ball

4-2-2007, against the Rangers, K-Rod put something on the ball repeatedly during the 9th inning, and wasn’t even subtle about it. First, I’m going to admit these are bad pictures. Patches welcome, as they say in the open source world. Or suggestions on how to get better stills — but any set of stills isn’t going to be as good as watching it yourself: if you’ve got, it’s worth checking out.
to Wilkerson
1: wipes brim of cap during long walk around mound, ball
2: video cuts back to him too late to see. 94, ball
3: grabs, rubs brim of cap, (2:48:28 on the feed)brings hand down, touches back of hand to back of jersey, rubs hand on jersey leg. 95.

4: nothing, 94, strike
5: grabs, rubs brim of cap (~2:49:15, same deal, running thumb inside) quick jersey touch. 95, strike.

6: video cuts back to him too late to see, fouled
7: good thumb work while walking back to the mound, 94, fly to center

to Laird
8: walking back to the mound at ~2:50:20, he crabs the brim and works the thumb for a couple seconds. Ridiculously blatant. Ball.

9: no camera, 94, strike
10: late camera, ground to 2b. Touches cap brim, thumb thing.
to Kinsler
11: no camera, 95, ball
12: no camera, 94, strike
13: crowd shots, 94, foul
14: ~2:52:47, off the rubber, he does the cap brim thing again, touching jersey before and after. Ball goes into the dirt, Napoli swings, ball’s picked off the ground and he’s tagged out
Compare the movement on those pitches to the movement on the fastballs where he clearly doesn’t go to the hat brim.
Also, watching the video, it’s a lot more striking than stills convey — it’s clearly not a cap adjustment, but something else entirely. He grabs the front of the cap and then rubs his thumb on the underside of the cap, picking whatever it us up. On the video, it’s quite striking.
Update: check out this still, where he’s tilting his head, courtesy of Sal Baxamusa

Update: from today’s game, you can repeatedly see that there’s a glop of something white on the underside of his brim on the right side. Here are two shots. First, the straight still:

And then, adjusting the levels to make that a little brighter

In the 4-3-07 game, there isn’t the kind of totally blatant grab-the-brim-then-rub-thumb repeatedly, but it’s even more clear that there’s something on his hat brim and he’s putting his thumb right on it.
Selected timings of shots of K-Rod’s brim, for your own reference:
2:46:07 (good)
2:46:18 (good)
2:47 (good)
2:52:30 - decent shot of the brim
2:54:50 - decent shot of the brim
2:56:48 - decent shot of the brim
2:57:50 - nice shot of the brim followed by K-Rod putting his thumb right in it