In a past life I was a full-time golf instructor. This gave me tremendous insight into the mechanics of the human body when performing other physical activities, including swinging a baseball bat. I have also taught many a juniors how to swing a baseball bat during my time as a little league coach. I may not have the credentials of Mark McGwire, but I certainly do know my kinestheology.
Now there are several mechanical differences between a golf swing and a baseball swing, but the majority of those are related to swing path and the imparting of direction based on bat angle over face angle. The path a bat takes is obviously much more horizontal to the ground than in a golf swing, and mostly a baseball player determines the direction the ball goes based on the angle the bat is at during the time the baseball makes impact with the bat. But the motions bear a striking resemblance and is one of the major reasons why baseball players gravitate to golf so easily.
In this series I hope to walk you through some of the mechanical inclinations of a batter and discuss some of the strengths and weaknesses of the players swing from the perspective of a guy who just kinda knows things. I don't proclaim to be the next specialist that the D-Backs need to really hit the ball better, but I know more than the average Joe probably.
We will break down the swing into sections. First, the setup. Next, the initial move. Then the motion toward the ball as it approaches the strikezone. Followed by impact, follow through, and finally the finish. These are the stages which every swing goes through and can be broken down to help identify where a batters strengths and weaknesses come from. We will look for things like balance, hand path, bat barrel path, lower and upper body torque, arm rotation, and the players upper body tilt at the plate.
Today's subject, Aaron Hill.
On the left we see Aaron in 2014, and on the right 2013. A few things to take note of. The bat is resting much more on his shoulder than last year where he was holding the bat slightly upward. You can see the bat is more horizontal this year. I have watched several of Aaron's swings both this year and last year and this is a very common difference this year. His "bat waggle" is much more toned down this year too. Last year he would lift and drop the bathead off of his shoulder, but ultimately get to this high bathead position just before the pitch was delivered. This year he is much calmer in the box.
His stance is slightly more closed, but very very slightly. If you look closely his new stance on the left actually looks more relaxed as his upper body isn't as twisted. This difference in rotation between hips and shoulders is an important aspect of power generation. In general the bigger the gap (more twisted) the better. However not all players are built the same. Goldschmidt in our previous review has a much stronger trunk and therefore requires less of a gap in rotation to generate some tremendous torque.
As the hips turn open the shoulders will turn with them. So if the player starts with the hips open, their shoulders will open earlier in their swing. This makes it easier for a player to get to an inside fastball because they can be quicker to the ball, however it becomes much harder for the player to hit to right field. This is why Aaron is known as a pull hitter. Now that Aaron is starting to swing with a slightly more closed stance in 2014 he can turn his back further as the pitch is being delivered. This allows Aaron more room to swing toward right field and let the ball get deeper into the strike zone.
Again small differences between last year (right) and this year (left). The bat angle was steeper last year which caused his swing plane to be more vertical. (Swing plane being a 2 dimensional area which the bat travels along) A more vertical swing means a player can get to the lower pitches but will struggle with the higher pitches. Inside and low pitches are especially dangerous for the pitcher against the old Aaron Hill. Aarons strength has always been the low inside pitch. This year he is trying to work on getting good swings to the outer half of the plate.
You can see a bit more of his back this year than last year. Look carefully at his name on the back of his jersey. You can more clearly see "Hill" on the left than on the right (not just because of picture pixilation). This is because he has rotated his upper torso further than last year.
His front foot placement is also something of importance. Notice how this year it is more in line towards the pitcher than last year. This will make his stride go more up the middle and help him swing back towards the pitcher rather than always to left field.
There is a domino effect in place here. The more neutral setup affects his front foot placement, which affects his hip rotation, which affects his shoulder rotation, which affects where his hands go during the swing. This small change in foot plant and slightly more closed setup changes the whole sequence. In golf terms this is called the "Kinetic Sequence" or "Kinetic Chain". One part of the body pulls or pushes on other body parts and they all must be done in a properly timed sequence. It is no different in Baseball. When you know how these small changes affect the bigger outcome, you can make simple adjustments to make yourself a better player.
On the left we can see Aaron reaching out to get the ball which is out over the outer 3rd of the plate. As a player has to reach out to get to a pitch you will see their butt stick out to counter balance. Less torque is able to be transferred to the upper body from the lower body. This is why "opposite field power" is such a rare thing and almost entirely reserved for the stronger upper bodied individuals. The more a player relies on their body to produce the torque (gap between shoulders and hips rotation) the harder it is to generate opposite field power.
You can also compare where Aaron's head is from the picture before. He is "diving" out over the plate to reach it. This action moves the axis of his swing. If you recall when we looked at Goldschmidts swing I mentioned a slight PULL BACK of his head which helped increase bat-head speed. In Aarons swing on the left he is doing the opposite. This shifting of the axis actually slows down the bathead slightly while at the same time helps to move the swing path inside to out. If you move the axis of the swing, the bat path will follow in that direction.
Also observe the left arm. Notice how much more horizontal it is this year than last year. This is partially because of the pitch location but it is also because of the position of the bat during Aarons initial move. Remember how the bat was pointing more toward the ground in 2013 after Aarons initial move? This year his bat was more horizontal and that allows Aaron to reach out for the ball much easier this year. With such a vertical bat last year, the pitch on the left would have been fouled off or swung on and missed in 2013. This year it went for a 2 RBI single that almost got to the wall in right field..
I'll also point out where his front foot is relative to his back foot one more time. Last year's home run was on a center cut fastball hit into the left bleachers. Aarons back foot this year actually dragged behind him really giving him that little bit of extra time to swing toward right field.
I think the most startling difference between these two images is the plate coverage. Look at how far over the plate Aaron's bat is on the left. The pitch is over the outer 3rd of the plate and he's still nearly hitting it up on the trademark. His hands are LEADING the bathead. Meaning, his hands are closer to the pitcher than the barrel of the bat and that's why the ball goes out to right field. On the right Aaron has fully release the barrel and the bat is actually starting to make it's upswing. This slight angle upwards is what helps lift the ball out of the park. You can look at the extension of Aaron's right arm to see the very distinct difference of where the bat-head is at impact and how he's trying to manipulate the angle the bat is at for each one of these hits.
Interestingly Aarons arms are much more rolled over in 2014's swing and much higher. This is a common characteristic of any player who is trying to swing out towards opposite field. The hands will be higher as the player doesn't twist so much post impact. They will also have much more weight on their front foot preparing them to come out of the box quicker. Aaron's home run on the right has his shoulders and hips much more open and the bat really being pulled AROUND his body rather than up and out. Both pictures show amazing balance despite two completely different outcomes and swing types.
In both swings Aaron has finished fairly significantly on his front foot with very little weight on his back. Despite a lack of speed to first base Aaron is actually very quick out of the box. He is clearly leaning TOWARD first base at the end of every swing which gives him just a little bit of a head start.
Aaron is a comfortable pull hitter and always will be. Anything inside is hittable. Even up and inside, however low balls are really his specialty. Aaron is also VERY quick to the ball which makes any pitch dangerous. He can wait on breaking balls and off-speed pitches, but now this year he's adding plate coverage to his repertoire. If he keeps it up, Aaron may have an 80+ RBI season.
Aaron is still susceptible to fastballs out over the outer 3rd of the plate. Despite being quick to the ball, his bat is not in the zone for that long and it is not a very level bat. It tends to be more of a vertical swing which can really get to the low and inside pitches, but he will struggle hitting the outside pitches. It's simply a matter of how long the bat stays in the hitting zone.
How To Pitch To Him
Fastballs outside and change ups inside. Until Aaron can prove consistent ability to get the bat out over the outer 3rd, it will always be the right place to go. Because of how quick he is to the ball, your best chance to miss his bat is to speed it past him outside, and try to get him to pull a few foul by coming inside with a change up. If he does hit the change up, chances are it will go further left. But be careful with the inside change up. If you leave it over the plate or throw it too fast he will catch up to it and it'll go over everyone head.
As a side note, teams SHOULD be playing an infield shift on Aaron with outfield having a slight shift left as well. Chances are good anything in right field will not be on the ground and he won't hit it down the right field line. Not for now at least.