In Part One of this series, I made a case for swing time as a major swing grading criteria. I made the point that bat speed is hard to quantify and compare between players. Meanwhile, swing time is easy to measure and compare. We saw that the majority of MLB hitters have 5 frame swing time, while elite hitters swing a little quicker and some - oh, how do I say this - lesser hitters take a little longer. If you are wanting a requirement to be a MLB hitter, a five frame swing is about as good as you are going to get.
But think of the five frame swing as a requirement - not a method. It is what hitters do in those five frames that really make the difference. And for that, I like to use another measurable and comparable metric - the swing path.
Before we go too deep, let's take a look at the current swing technique taught by hitting instructors. Below I have two videos from MLB hitting coaches (yes MLB hitting coaches) demonstrating their vision of the correct swing path. Cues you will hear to go along with this instruction are "be short to the ball," "swing down and through the zone," and "stay on top of the ball." I use software to track the swing path their bats take. (You can watch the videos here and here to see I am not taking it out of context).
Here I show the swing paths of the two instructors with a path of a 90 mph fastball overlain. You can see that the paths aren't very forgiving. If the timing is just a bit off, the swings are going to result in groundballs or worse infield pop-ups or even worse no contact at all.
A perfect example of a MLB player with this type of swing path is the Giants' Brandon Crawford. Crawford even speaks of his swing path in this article with Tim Brown. So far Crawford has yet to have a season north of .300 wOBA and wears out the infield grass at Phone Booth Park to a tune of 49% ground-balls. Crawford's swing time (and probably bat speed, though hard to say) is just fine. It's his swing path.
Now let's look at another player's swing path, this one from Josh Donaldson.
We see that Donaldson's swing path is quite a bit different then the coaches' or Crawford's. First, Donaldson's path is much longer in distance. Donaldson isn't being "short to the ball." Instead, Donaldson gets his bat on plane with the pitch much more quickly in his swing - behind his rear leg, resulting in a longer swing. Second, Donaldson's path tracks the path of the pitch much better. Donaldson can be slightly off with his timing and still make solid contact. Intuitively, these factors make sense. Sense players' swings are typically around .167 seconds, having a longer swing means their bats are moving faster. Also, giving yourself more room for error in your swing path will result in better contact on balls just missed. Yes, Donaldson's swing path is actually an uppercut. A slight uppercut swing path has been shown many times to be optimal for performance, including one of my favorite books The Physics of Baseball by Robert Adair.
Let's look at some more players' swing paths. Below is Mike Trout. Trout combines elite swing time with a perfect swing path. Plus he is built like a linebacker. Yeah, he is going to be good for a while.
Below is Troy Tulowitzki's path. Again perfect.
Miguel Cabrera. Same.
Somebody asked me about Bonds last time so I might as get it out of the way on this one.
Just like swing time, the swing paths of successful hitters are very similar. Swing paths can give us insight into hitters, like Josh Reddick.
Reddick's path is shorter and different than the players above. See how in the beginning of his swing, the line isn't smooth like the hitters above. Reddick's swing path is very direct to the hitting zone, but this cuts some of the margin from his swing. Also, since Reddick's bat gets to the zone in the same time as the hitters above but in a shorter path, he has less on his swing deeper in the zone. This is why I am so hard on Reddick for trying to become an opposite field hitter. His swing path simply does not allow it. The more he tries to hit oppo, the more weak flyballs to left field. (For more on how Reddick could improve his swing path, read this). While Chili Davis works to shorten Reddick's swing, I say he needs to lengthen it. Reddick's swing power is out farther than most players and is best suited trying to pull the ball.
Reddick's path is similar to Moss' path. See how instead of a backwards "C" Moss' path is more of backwards "L."
Same as Reddick, Moss doesn't have much speed going into his path's corner, and won't have much success hitting the opposite way (opposite field hitting is usually a little deeper in the zone). It takes a little longer (in distance) to get his swing speed up, so Moss is going to be an out-front hitter as well (pretty obvious with both arms extended at contact). Unlike Reddick, Moss has embraced this and goes with what works for him. However, I am not advocating this type of swing path. It is very limited in where your power zone is (out front) and Moss is far-and-away the most successful hitter I have seen with this type of path. Due to Moss' strength and singular purpose of pulling home runs, he makes it work. But I wouldn't use his swing path as a teaching point and wouldn't have predicted his success.
There is a limit to length in a hitter's swing. Below is Yoenis Cespedes' path.
Instead of the bat starting over his head like the elite hitters, Cespedes starts his bat past his front shoulder. Cespedes' swing still clocks in at 5 frames, so we know he has tons of bat speed. But his swing path is so long it makes it hard to make consistent contact. When pitches are coming in nice and easy like in the Home Run Derby, sure Cespedes uses this bat speed to knock them in the upper deck. But I argue he could cut down on his swing path and have more consistent and better results. (If you are a golfer, think of Cespedes has having an overswing in the backswing.)
Like I did with swing time, I make the case that swing path is measurable and can be used to compare as well as improve hitters. Like for example, "Coco Crisp, you want to improve on that .285 wOBA from the right side in 2013? Well, let's work on your swing path. See how your swing path is too steep coming into the contact zone compared to Donaldson? Your swing doesn't have any margin for error."
Or Reddick. "So you want to become an all-fields hitter? Great. We need to work on your rear arm function to improve your swing path." Or Cespedes. "Want to make more consistent contact? Let's chop off a little on your swing path. And fix your front leg's function while we are at it." Or Jemile Weeks (too late I guess.) "You sure are hitting a lot of weak ground balls. Let's look at your swing path."
Or Michael Choice (again too late). "How come your power hasn't shown up past A ball? Let's look at your swing path. See, it is too steep going into the hitting zone. We need to add some loft to your swing. We aren't chopping trees here."
Anyway. That's two of my three major swing grading criteria. The third is how players' swings will allow them to adjust to varying pitch speeds. That one is more subjective than the first two, so I will have to figure out a way to turn it into a post.
Hopefully I have done a decent job showing some common swing traits among successful hitters. And that these swing traits can be quantified, compared, and be used to improve performance. At the very least, I hope the next time you read a scouting report about a prospect with a short, compact swing with lots of bat speed you will take a second to think about swing time and swing path before buying his jersey.