If there is a one word description of the game of baseball, it could be anything. Speed. Grace. Strategy. History. It's an exercise in pointless athletic endeavor, played under a set of generations old rules like balls and strikes, fouls and home runs, and played under a set of constantly evolving economic and political rules; Rule IV, Rule V, CBA. There are the old heroes and villains. There are the fiery young kids in the stands and in the bullpen and in the outfield. There are the moral conundrums. Hard slides. Beanballs. Gambling. Steroids. Some like their players squeaky-clean, and some know the players on their favorite team go straight to the bars after practice. Success is predicated on a million factors, chief among them being two opposite and equally powerful forces:

Talent and luck.

And what's in that word talent? Control. The ability to control the outcome of pitches, at-bats, contract negotiations, player development. Luck is the same. Luck is the absence of control. Perhaps baseball is nothing but levels of control.

Allow me to introduce myself: I'm no-one. I don't know much more about the game than anyone else who knows the rules and teams. I have little to offer in the way of perspective. I have no credentials. My writing is going to mostly consist of series of facts, laid out to foster understanding and perhaps eventually to argue hypotheses. My specialty so far is medicine. That's where I begin today, and I'm going to talk about control. As with any general concept, it applies to baseball in many ways. Medicine is the same.

Pitchers can control their own bodies, and they exploit that control to help them control the baseball. Sometimes that control allows them to command millions of dollars. It comes and goes. As soon as the ball leaves a player's hand, it's out of his control, and even though pitchers control their own bodies, there's a lot about themselves they cannot control. Often, their muscles and ligaments shred before they ever get to sniff the fortunes and glory they're dreaming of.

The reason athletic mechanics are important is that good technique increases the life span of the structures involved. And yet there are elements that are beyond the control of the player in this realm as well. Those elements are the player's anatomy.

Swerve.

The scapula- the bone commonly known as the shoulder blade- is the origin of the muscles of the rotator cuff, and it makes up the bony part of the shoulder capsule around which the labrum is arranged. It's the source of the rest of the joint capsule as well. 

via upload.wikimedia.org

This isn't the only view of the scapula that is normally taught, but it's the most useful for our purposes. We are looking into the shoulder from the left side, and the upper arm bone is absent. The large, pear-shaped surface around the number two is one articulating surface of the shoulder. The head of the bone of the upper arm plugs in there and is surrounded by connective tissue. Tendons and muscles of the rotator cuff wrap around this capsule under the two bony hooks (numbers one and 3-5). Without getting too technical, the bony anatomy of the scapula can have a dramatic effect on the integrity of the muscles and tendons of the rotator cuff. You've heard that genetics and anatomy can cause players to have longer or shorter careers- here's one small example of how:

via www.aafp.org

(note the perspective is flipped, the first scapula was a left scapula, the above three illustrations of a right scapula)

The bony hook on the left side of each of the three scapulas above is called the acromion process (opposite side and numbered 3-5 on the first picture). Injuries to the rotator cuff have a few different names (bursitis, impingement syndrome, rotator cuff tears), but most commonly these names refer to similar injuries to the supraspinatus tendon. This tendon runs under the anterior (front side- right side in the illustration above) portion of the acromion and is confined between that bone and the bones and joint capsule of the shoulder. The picture above shows three common types of acromion- all of them are perfectly normal, but one of them is associated with 80% of rotator cuff (supraspinatus tendon) tears. This is evidence that the hooking of the front of the third acromion type increases the wear on the supraspinatus dramatically.

The underlying cause of these anatomical differences is that the bones that make up the scapula do not fuse into a single bone until some time during a person's childhood (in some people, the bones never fuse completely, resulting in adults with a separate bone called the os acromiale in the place of the acromion process). This is one of the many reasons that a pitcher's specific injury outlook cannot be based simply on mechanics or video and is best summed up as a set of probabilities and compared with the larger field of athletes.

Also, nice to get re-acquainted with you all. See you soon.