I've always had an interest in Penny, he's a guy with a power "rising" fastball---watch his cheddar throwing in the All Star Game---but was always able to get groundballs somehow. Side note: that paradox is one reason I've guessed that he's been able to keep a HR/FB% a little bit lower than average, he's apparently pitching down in the zone with a high RPM backspin fastball, when the ball comes off the bat it should have less backspin->not as much loft. Or I could just be making shit up.
In any case, he's obviously been a good fit for the Duncan philosophy despite not having the typical fastball sink of a Duncan reclamation project, sporting a nifty 53% GB% vs. 45% career while basically walking no one .94 BB/9 vs. 2.86 career. He's never been a big K-guy, and also in typical Duncan style he's also at a career low 4.71 K/9. If you didn't watch him pitch, you'd think this guy was Suppan with better command.
Duncan has certainly made a mark with Penny's gameplan: he's essentially been a 3 pitch pitcher, throwing a (by far) career low ~49% fastballs, (by far) career high 37% splitter/changeup, and near career low 14% curveballs. To be honest I can't remember Duncan changing a pitcher's pitch distribution quite this much as Penny is a dramatically different pitcher than he's ever been. Props to Penny/Duncan for having the balls to change so much.
Not only is he throwing different pitches, but he's throwing them differently. His FB is still coming in at 93.7, but the one thing that has stuck out to me watching him is how his splitter/changeup has been coming in at 86-90 averaging 87.9. He has to have gone to a different grip or something as he's picked up about 2 mph on his splitter; you'd think that'd be a terrible thing (FB/CH velocity differential is hugely important), but it seems he's using it much more like a sinker than a true mess-with-your-timing-changeup. On to the PITCHf/x from TexasLeaguers.com
The first thing that jumps out is the shotgun of.....stuff....in the upper left quadrant. He's throwing a bunch of FB/Splits with all kinds of different movements. He's throwing the super riser fastballs with 15+ inches vertical movement and then dropping the split which can essentially moving like a Lowe sinker when he really gets it sinking. Then he's cutting his fastball almost to 0 horizontal movement and running it all the way out to -10-12. He's throwing a lot of the same pitches, but not one of them are likely to be moving the same way and I can easily see how it'd be hard to square him up. On top of that, he obviously knows what he's doing movement wise because his command has been excellent.
I think his curveball kinda sucks standalone, but when it's basically impossible to be sitting on one speed on his FB already so he can mix that in the 14% of the time and keep it effective (example 50,425 why fangraphs pitch values have to be looked at in context).
Again he's basically throwing up a bunch of stuff with a wide range of overlapping velocity anywhere from 85-97, and then dropping in the curveball.
Really the summary is pretty simple, he's pounding the zone (career high 65.7% strikes) with bunch of stuff pretty equally spread between 85-97 coming from the same armspeed, and then on top of that it's all coming in with very different movement. It's a simple scouting report, but it's a lot easier said than done to not get your timing messed up by that.