Everyone is looking for keys to get players to elevate the ball. One important point is certainly the so called attack angle. The attack angle ist the angle of which the bat attacks the ball. Baseball used to teach swinging down but now you actually want a small uppercut. Players use different cues to achieve that. Common cues are for example leaning slightly back to the catcher and work up with the front elbow.
Up in the zone elevating is pretty easy. The league average LA in the upper third of the zone is 20 degrees. Even christian Yelich averages 15 degrees in the upper part oft the zone. In a prior analysis I also found out that LA in the upper part oft he zone has little influence on wOBA. 170 out of 182 hitters last year averaged 10+ degrees.
That is very different low in the zone. The league average LA in the lower third was just 5 degrees and over 30 guys actually had a negative LA.
|WOBA bottom 20
|WOBA top 20
|Up in zone
|Down in zone
So the key for the low LA guys is definitely still to lift the low pitch.
So how can this be achieved? You definitely need to swing up and you also need to avoid rolling over and hitting a grounder to pull field which is what the sinkerballers try to achieve.
One theory is that on low pitches you tilt the shoulders more down and hit with the bat pointing more to the ground. The cue is that for high pitchest he bat turns more like a merry go round and on low pitches more like a ferris wheel.
This ferris wheel like path makes sure that the bat comes through more straight through from below rather than going across the ball which leads to rolling over.
Mike Trout is so good at this that he is able to sometimes even hit down and in pitches to dead center for a bomb while most have to pull that ball. Jeff wrote a nice article about this https://www.fangraphs.com/blogs/jabo-mike-trout-has-a-new-trick/
Of course this ferris wheel path also has his disadvantages, for example Trout used to be very bad on high pitches the first 4 years of his career. Still he got away with that because most pitchers would only pitch up like once per at bat and not live up in the zone so Trout would just take but ideally a batter would flatten out the bat up in the zone and swing steeper down which Trout actually did last year causing him to improve up.
But the traditional level bat, level shoulders cue is definitely hurting on low pitches and made the sinker so popular. Now that more guys learn the new swing path the sinker doesn’t work as well anymore but there are still hitters who struggle down (like Hosmer and Yelich).
The pitch up is getting more popular but it can not suppress launch angle. The high pitch lifts itself, when a pitcher pitches up he needs to compensate for the higher LA by more pop ups, lower EV and more Ks.
It is a good sign that Hosmer now thinks about swinging up more but if he wants to increase his LA he either needs to stop swinging at pitches in the lower third and target pitches up or change the rotation axis of his bat to more vertical on top of his attack angle because if you swing up but across the ball on low pitches all you do is hitting your grounders with more topspin.
I measured the vertical angle of some good and bad low ball hitters. On the left oft he picture you have Yelich and Hosmer and the other pics are Ortiz, Trout and Votto who are all excellent low ball hitters. All pitches I chose were about knee high and on the inside of the plate because that affects the bat angle.
you can see that yelich and hosmer have much flatter angles than trout, votto and ortiz (mid 20s degrees vs 40+ degrees)