Since David already did a great piece on Brandon Morrow's PITCHf/x analysis, I'll just stick to his pitching mechanics.

Brandon Morrow stands 6'3" 185 lbs and was drafted 5th overall in the 2006 MLB amateur draft by the Seattle Mariners. A RHP, Morrow primarily relies on his plus fastball to get hitters out:

Morrow is known for his blistering fastball (with some pretty good movement), but concerns have been raised about the long-term health of his arm, given that he spent two weeks on the disabled list with a sore shoulder at the beginning of 2008. 

Let's take a look at those mechanics...

Below is the image that we'll use for analysis of his pitching mechanics:

This pitch was strike three to Manny Ramirez (then on the Red Sox), clocking in at 99 mph on the Safeco Field radar gun. I have my doubts about it actually being 99 mph, but that's another debate.

Astute readers will notice a few things right off the bat:

• He has a "plunge" arm action that is very similar to Tim Lincecum.
• He loads the arm horizontally in a "scapula loading" pattern.
• He makes the "Inverted L."
• He has significant flexion in the wrist, which Dr. Marshall calls "grab."
• He has significant gloveside flyout.

There are a few things that are very troublesome about this sequence of images. First of all, note how in the first frame that his arms are in the classic "hung arm" pose that Tom House used to teach and is evident in pitchers like Mark Prior, Anthony Reyes, and especially Barry Zito:

I used to think the tension in the wrist wasn't a big problem, but after further research, I've concluded that the "grab" can cause "looping" (Dr. Marshall's terms), which essentially lengthens the driveline to the target and forces it in an arc, rather than a straight line. This part of Morrow's arm action is prevalent when we take a closer look at his arm action:

Compare this with, say, Tim Lincecum:

Note how Lincecum's arm action is more direct to the plate, while Morrow's "loops" back around and to the target due to his grab. Lincecum also is closer to a vertical forearm at release, which is ideal, but that's a different discussion entirely.

Morrow's arm is not vertical at footstrike / shoulder turn, as evidenced in the hung arm animated sequence. This will increase the distance that his arm passes through the external rotation phase and force it to lay back violently - experiencing "forearm bounce." This will increase the stress on the UCL as well as the Subscapularis and Supraspinatus in the shoulder. (Pitchers who have significant forearm bounce are Joel Zumaya, Kerry Wood, and Billy Wagner.)

Morrow's arm action is troubling. I would grade it Below Average.

Ball Release / Followthrough

Morrow points the PAS shoulder at the target fairly well, but he flies open with his glove arm, just like Scott Kazmir. He also has an abrupt finish, which is troubling and probably the result of not throwing against a firm front side. However, Morrow mostly keeps his head still, which should help with command/control of his pitches.

Overall, though, I don't like his deceleration. I think it's Below Average.

Conclusions

Mariners fans are pinning their hopes and dreams to this kid - and rightfully so. He'll always be looked at as the kid taken over hometown hero Tim Lincecum, and while his pure stuff might not be as good, it's certainly not far behind. Unfortunately, there's a lot to worry about with Brandon Morrow compared to Tim Lincecum - Morrow's late positioning at footstrike, his "grab" in the arm action which leads to looping, and his poor followthrough combined with a short history of shoulder problems leads me to wonder how well off he'll be in the 2009 season when he'll be expected to make a full season's worth of starts.

I would treat Brandon Morrow as a significant injury risk in his career, though probably nothing serious will happen in the next few years. Morrow has too many flaws to correct at this point; he is already an MLB-polished pitcher with a lot of expectations placed on his golden arm.