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Chris Perez probably needs to improve his control to become a legitimate major league closer.

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(Yes, that is really Chris Perez pitching in the image above.)

The SB Nation blogosphere is rife with stories about the first big MLB "deadline trade" in 2009.

• Let's Go Tribe: Mark DeRosa has been traded to St. Louis
• Viva El Birdos: Cardinals acquire Mark DeRosa for Chris Perez, PTBNL
• Bleed Cubbie Blue: Cardinals Acquire Mark DeRosa JESUS GOD WHAT ARE WE GOING TO DO NOW

Here at Driveline Mechanics, we'll be running three stories about the trade - Jeff Zimmerman has already taken a quick PITCHf/x look at Chris Perez, while devil_fingers will be looking at the trade from a "sabermetric" approach.

Since this is as good a time as any to update my own site (boy, it's been awhile), I'll be taking a look at Chris Perez from a mechanical standpoint. First, as an Indians fan, I have to say that I'm enthused with the trade - while flipping Mark DeRosa means that Mark Shapiro has given up on the 2009 season, that was a reality that was worth embracing to get a guy with big-league stuff, if not big-league control. Oh, and a PTBNL, too! A friend of mine who posts on another sports forum made this interesting (and humorous, if you're not a Cubs fan) comment:

...if you combine this year's deal with last year's deadline trade, Shapiro has essentially swapped five months of a versatile .270/.340/.455 rental player in exchange for Carlos Santana, Chris Perez, Jonathan Meloan, and a fourth player. In comparison, Jim Hendry dealt six months of that same player for two old, generic relief prospects and a young one with poor control.

Ba-zing!

Less talk, more video after the break...

Chris Perez is a fireballing RHP with an average velocity of 94.0 MPH on his fastball. That's good for 33rd hardest in the majors amongst relievers. (source: Fangraphs) As a fun note, Joel Zumaya's average fastball is 99.2 MPH. That's absurd.

Perez mainly relies on his fastball/slider combo to get hitters out. Here's what the split looks like:

As you can see, Perez has pretty good movement on his fastball that tails in to a right-handed batter. In the image above, he throws it for a backdoor strike three. His slider is pretty devastating, as he buries it in the dirt to get the hitter to chase on 0-2.

We'll use this fastball image to take a look at his mechanics at a more manageable pace:

Tempo: 17-18 frames from maximal leg lift to footplant, which is excellent. Anything equal to or under 20 frames is ideal. Chris Perez really gets to the plate quickly.

Arm Action: While not a classic "elbow lifter," he still has an arm action that can be called the "Lateral V." The Lateral V occurs when a pitcher creates a V with his pitching arm as viewed from above and raises it to driveline height in this crooked position. In the following still photo, you can see Perez at the approximate maximum lateral displacement of his pitching elbow beyond his acromial line:

Needless to say, I'm not enthused with this arm action. It often causes lateral displacement of the pitching arm and subsequently represents a timing flaw, since the arm needs to get from this displaced position to the high-cocked position quickly. In doing so, this causes the pitching forearm to lay back violently in shoulder external rotation, and while the result may create a higher value of Maximum External Rotation (MER) and thusly higher velocity, it is also the cause of "Late Forearm Turnover" which places a significantly high load on the ulnar collateral ligament.

As an aside, ASMI concluded the following (emphasis mine):

A pitcher with increased shoulder external rotation, faster pelvis and upper trunk rotation, and greater front knee stabilization and extension will throw with greater ball velocity. Source: ASMI

Many pitching analysts/gurus will tell you that you need to increase MER to increase velocity. However, while high values of MER correlates well with release velocity, it also correlates well with injury. This is not surprising, as you can find many studies talking about harder throwers being more likely to suffer arm injuries, but advocating that pitchers should focus on increasing MER as a way to increase release velocity is dangerous. (I will have a more lengthy article on this in the near future.)

Ball Release: In general, I prefer high three-quarters to near overhead releases, as it eliminates side-to-side movement of the baseball and thus avoids "Pitching Forearm Flyout." The further the arm nears a sidearm release, the less possible it becomes to pronate through release on any given pitch. As a result, this causes the elbow to "slam closed" and causes the olecranon process to slam into its fossa. This in turn causes the ulna bone to elongate (loss of flexion in the pitching elbow) and can break off pieces of the hyaline cartilage, which causes bone spurs. So, when you see a ball release like this:

You start to cringe. It reminds me a lot of J.J. Putz:

Followthrough: Perez uses the glove arm well to mirror his pitching arm and finishes with the glove near his shoulder, which I really like. Unfortunately, with a near-sidearm release, the high glove finish can't help him pronate through release. You can see that Perez tries to keep his eye on the target for as long as possible, probably because Dave Duncan or another pitching coach told him that this would improve his control. The fact is that this isn't true - ASMI has been unable to correlate head pitch/yaw with the ability to throw strikes. Common sense would tell you that the plate isn't moving, so there's no reason to look at it the entire time. For an outside example, golfers are often instructed to keep the head down and to not pull off the ball, yet no professional golfer actually has their vision locked on the ball at impact. It simply does not happen.

Perhaps as a result of Perez locking eyes with the catcher's glove, he has below-average shoulder rotation through release. While he has significant forward trunk tilt, he does not complete rotation to help relieve strain on his pitching arm. This abrupt stop of the shoulders causes the pitching arm to decelerate across his body and to recoil, stressing the posterior muscles of his shoulder.

Overall, I'm not terribly enthused with what I see from Chris Perez. As an Indians fan, I hope that Chris Perez can avoid the disabled list if he's used as a reliever, but I forsee elbow strain/inflammation on the horizon for him, with possible bone spurs and UCL tears/rupture.