Thursday, November 21, 2013
j teaches us all some cool stuff: Former (and potential Future) Yankee Robinson Cano
Clay and Mike K. are planning to review the development of the Yankees minor league players, and asked if I would be interested in providing some swing analysis to compliment their discussions. I said yes. I wanted to get things started with a primer using Robinson Cano’s swing.
The first step is where Cano, and other good hitters, gather their weight into their back leg.
Note that I said *into* and not *over*. Cano isn’t drifting over his back foot with his weight. Instead, he’s rotating in the angular direction opposite to the direction that he’ll swing in, loading the revolute ball and socket joint in his back hip. This also serves to close, or what Ted Williams refers to as ‘cocking’, his front hip.
The next stage of his swing is where Cano accomplishes the stretch shortening cycle, a well documented phenomenon whereby an eccentric contraction of a muscle precedes concentric contraction and results in a greater output. You can think of it like stretching a rubber band and releasing it. Players have a few ways of accomplishing this, and Cano’s approach is to stride slightly forward – maybe just a few inches – as part of the action of shifting his weight from his back side to his front side while simultaneously loading his shoulders into the opposite angular direction. Finally,
There are a few important things to note here. First, these actions must happen at the same time, otherwise a hitter is not going to achieve the stretch-shortening cycle. Also, Cano isn’t pushing off his back foot towards the pitcher. Instead, he’s pinned his back foot into the ground (using his cleats) and rotating his (revolute) ankle joint in the opposite angular direction of his swing. Because that joint is pinned, a force in the opposite angular direction of his swing is going to create movement of his hips in the angular direction of his swing. Finally, you’ll notice that the simultaneous loading of the hands and shifting of his weight stops as soon as Cano’s foot hits the ground. At this point, Cano’s about as leveraged as he can get and is ready to use his hips and core muscles to pull his hands through the hitting zone. Once Cano’s front foot lands, the potential energy that he’s stored in the muscles that connect his front hip and back shoulder starts to decrease. So, once that front foot goes down, ideally Cano should start the rotation portion of his swing. We’ll see in the next image that this is exactly what he does.
Now we see Cano rotating, using his hips and core muscles. This phase really starts a little before Cano’s front foot lands – as you can see, the front foot landing coincides with a little bit of hip rotation. This isn’t a flaw – in fact, it’s an important triggering mechanism for the rotation phase of the swing. His front leg is stiff, which provides a pivot for rotation. His back elbow is now tucked into his back hip, making his hips, torso, shoulders, elbow, and wrists a rigidly coupled system, so that they are all moving together. The rotation of his hips have created a moving angular reference frame, inside of which the stretch-shortening cycle has created a system with potential energy that is becoming kinetic energy, with velocity that’s added to the angular velocity created by his hips. Also notice how compact Cano is. By keeping his arms close to his body, he’s not only created a very rigid couple between his hips and his bat, but he’s also decreased his moment of inertia. By decreasing his moment of inertia as much as possible, Cano is minimizing losses in the transfer of angular momentum at his hips/core to angular momentum at his shoulders/arms/wrists/bat. We see the same effect with ice skaters – they spin more slowly (so, with less momentum) when their arms are extended, and then tuck their arms in to speed up their spin.
Strength through this motion is basically the most important part of the swing. Cano’s using his hips to pull his hands through the hitting zone.
He’s keeping his hands back and the bat on the outside of his back shoulder. It’s important to understand the role of the hands here. The hips are doing all the work, and the hands just need to keep the bat in position to make contact with the ball. The best way to do that is to travel on a plane that matches the trajectory of the pitch. Based on the height of the mound, the trajectory of a pitch makes about a 6-8° angle with the ground. So, the bat needs to travel on a plane that matches that angle.
Here’s another good example of what happens as a result of strong rotation from the Home Run derby in 2011. Notice how the extreme rotation of his hips literally pulls his back foot off the ground.
There’s not much to discuss with the finish. A good swing has the bat accelerating through the point of contact and creates a bat with a lot of angular momentum. A good indication that the bat is on the correct plane is that it the finish will be at the opposite shoulder.
There are a lot of subtleties and intricacies that I glossed over here, but I wanted to give everyone a sense of what are the pieces that make up a good swing. We’ll likely get into them when we look at some of them minor league guys and discuss problems that they’re having and what the root cause might be.
So, what concerns me about Cano’s swing? Well, there’s not much, but there are a few things:
- When Cano gathers/unweights his front foot, he does seem to drift back a little bit. It’s not a lot, but it’s there. Drifting or swaying backwards creates a balance issue. Because Cano sways back a little, he needs to drift back forward to regain his balance. He seems to incorporate this into his stride and uses it to get separation between his back shoulder and front hip. A hitter who incorporates this sway back/sway forward approach is potentially vulnerable to pitchers with large velocity differences between their fastball and offspeed pitches.
- Cano’s unweighting mechanism is a leg lift. This is fairly common, but it is, in my opinion, a concern as any players physical abilities start to decline and will reduce their ability to maintain their contact rates. A better option is a toe touch, where you unweight your front foot but stay in contact with the ground, so you can drop your foot and start the rotation phase quickly. Of course, it’s not an easy thing to change, especially if there’s no problem with it now.
Thanks a ton to j for doing this. He’ll be providing us with more great stuff as Mike and I work on our pieces this winter. Hopefully we’ll do some in-depth prospect profiles at some point as well. - Snuggles
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