Tangotiger Blog

Thursday, March 14, 2024

Statcast Lab: Catcher knee height prior to pitch release

Just the first step in looking at this. The left column is the height of the left knee, the top row is the right knee. 

The most common position for the catcher is for the left knee (the glove knee) to be 3-5 inches off the ground, while the right knee is 17 to 20 inches off the ground.

We do see the catcher often enough with their right knee 3-5 inches off the ground, with the left knee 11-20 inches off the ground.  I should probably split this by bat-side (and maybe pitch-hand).

Having both knees up, 14-19 inches off the ground is the least popular of the setups.

I'll be looking as well to see how the called strike rate is affected based on the catcher stance.

(Click to embiggen)

Monday, January 15, 2024

Statcast Lab: Introducing Catcher Lunges

I love JT Realmuto. And it pleases me to no end that he would come out on top in various catcher metrics I've created during my time here at MLBAM working on Statcast. After I develop metrics, I always check to see how Kiermaier and Betts and Realmuto and so on do. He still comes out very well on throwing and blocking. And up until 2023, he was excellent in framing. 2023 however, he was very different.

When it comes to a very toolsy metric like what we have on Savant, the level of uncertainty is fairly low. Why is that? Because there is very little inference going on. Most fielding metrics, and really any of them pre-tracking, it's all about inferences. But here, we are simply reporting what was being measured or tracked. But, I know that seeing a number like -13 runs, when that is preceded by +7, +3, +4, 0 seems off.

Since I've started looking at the catcher locations on called pitches, I was interested in developing a new metric, Lunges. You know those pitches: the catcher is on one side of the plate, while the pitch is going the wrong way, so the catcher lunges to catch the errant pitch, even if it's in the strike zone.

The best catcher at Lunges (at least on 4-seam fastballs, RHH v RHP) is Matt Thaiss. You can see the description of the data I was going after in the previous article. In this one, I further limited it to pitches where the catcher was located on the inside part of the plate. He faced 21 pitches in the outside part of the strike zone, and all 21 were called strikes. That's well above the 85% for the league average. He caught 57% in the shadow area, where the league average is 38%. All in all, of the 58 pitches in these regions, he caught 34 that were called strike, while the expectation was 27. That's +7. Again, just limited to RHH v RHP on 4-seamers. Eventually, I'll make sure to cover everything.

Realmuto however. He only got 56% strikes on pitches clearly over the plate. When Thaiss gets to 85%, and JT is at 56%, that's certainly alarming. For pitches in the shadow area, JT only got 8% strikes (1 of 12), while Thaiss was at 57%. All in all, JT got 10 called strikes out of 36 pitches, whereas the league average is at 18. That's -8.

Now, I hear you, small sample size. Forget about: I hear you. I say it! You hear me. The larger point is that JT is at -13 runs for the season on all pitches. This is just one snippet to show where JT failed and where Thaiss succeeded. Given that Thaiss was -1 runs overall, this must mean that there was other areas where Thaiss did not do well. Lunges however, is where he did do well.

Now, off to watch some video of these two catchers to see if the eye test matches what we've just learned here.

Sunday, January 14, 2024

Statcast Lab: Proving with Science The Art of Framing

This is an exciting chart (click to embiggen).  This data is limited to RHH v RHP, where the 4-seam fastball comes in 2 to 3 feet above the ground, and on the 1B side edge of the plate. Remember that, every pitch we will look at are OUTSIDE pitches, pitches that land on the 1B side of the plate. These pitches are called strikes 50% of the time.  Of course, we know that how the catcher frames the pitch matters.  And I'll prove it for those who still don't believe it.

The top line is the side/side location of the catcher's wrist.  At -8 inches, that's the edge of the plate on the 3B side, and +8 inches is at the 1B side.

The column represents the number of frames prior to the ball crossing the plate.  At 30 frames per second, this means -10 is one-third of a second prior to plate crossing.

All good so far?  The percentages you see there is the eventual strike% call.  So, let's start with the most obvious thing here, the first entry that shows 22%.  What that says is that the catcher was setup on the inside part of the plate.  Since we know that all of these pitches land on the outside part of the plate, these must have been major misses.  You know when it looks like the catcher stabs at a ball, even if it's still in the strike zone, that it gets called a ball?  Congratulations, we now have proof.  Those pitches are called strikes only 22% of the time.

Now, look where the catcher is setup when the throw is perfect.  At the -10 frame, we see that when the catching wrist of the catcher is 2 to 7 inches from the center of the plate, that pitch is called a strike 60% of the time.  Which is of course way above the 50% average.

Now, the even more exciting part: look at the rows after the row labelled 0.  Remember 0 is at plate crossing.  So, at row 3, that's 3 frames after plate crossing.  And when the catcher's wrist is 3 inches from the center of the plate (remember for a ball that is crossing the plate on the black), that pitch is called a strike 80% of the time. So, this is the catcher drifting his glove back toward the center.

What about the catcher that just sticks-the-landing?  Well, look at that column 10, which means the wrist is 10 inches from the center, so beyond the black on the wrong side.  Those pitches are called strike only 5% of the time, when the point is 5 frames after the plate crossing.

Basically, you really need the catcher to give the perception of the strike in order to get the strike.  You can't just catch the ball and just stay there.

Statcast Lab: Catcher Glove and Intended Location, part 3 of 3

As we saw in Part 1 and again in Part 2, the gap in the final location of a pitch high/low (about 18 inches) is not equal to the gap in the initial location of the glove of the catcher (about 4 to 5 inches).  While there is certainly a directional pattern, the magnitude is not there.

This is why those early attempts at trying to measure how well a pitcher hits their target were doomed to failure from the start, at least those that were focused on the 2D portion of the strike zone.  The up/down location of the pitch just can't possibly compare in magnitude to the glove of the catcher, since the catcher is ALWAYS keeping his glove low.  The very highest the catcher is going to try to hold his glove is two feet off the ground, which is still in the bottom half of the strike zone (the middle part of the strike zone is about 30 inches off the ground).  So any pitch that comes in high will always look like it did NOT hit its intended spot.  Except the glove is not the intended spot, but a reference point.  You need to be able to convert the reference point into an intended point.

The side-to-side is a much different story.  There is a 6 to 10 inch gap in the location of the glove side to side, based on whether the pitch is intended to be inside or outside.  This is for a final actual location of the pitch of about 24 inches.  While still not the 1:1 relationship, it's somewhat better than the high/low location of the glove.  So, even if you are trying to measure command along ONE direction, the side/side, you still cannot just do a comparison as if the location of the glove is the intended location of the pitch.  Again, even here, you need to be able to convert the reference point of the side/side glove target into an intended point.

Can we get there?  Yes, it'll take a while.  We have alot of variables to consider.  This one is the easy one, with the focus on 4-seam fastballs, where the pitch is the straightest in terms of the setup (though even 4-seam fastballs have some natural tail to them).  What this really requires is a pitcher-by-pitcher understanding as to how catchers setup for each of their pitches, and how much the reference point represents the intended point.  I suspect that some clubs already do this.  We'll try to get this done as well, and hopefully get this data up for you to see.

Statcast Lab: Catcher Glove and Intended Location, part 2 of 3

Read Part 1 so that you are all caught up.

Thank you for reading Part 1, which focused on inside pitches.  Now let's look at how the catcher sets themselves up on outside pitches (click to embiggen).

Here we see a pretty muted pattern.  First, we start with the green line, which shows no pattern at all in terms of left/right.  So whether the pitch is intended to be high or low, the catcher does not set themselves up any different, on outside pitches.  This is very different from inside pitches.

In terms of having the glove closer to themselves or the plate (the orange line): it's a bit over one inch, or about half the effect of inside pitches.

Finally, the blue line, how high/low the catcher sets his glove for pitches intended to be high/low: this gap is the most pronounced at almost 4 inches.

So, overall, it is similar as with inside pitches in terms of total magnitude (4 to 5 inches), but directionally, on outside pitches, almost all of the shift is high/low.

Statcast Lab: Catcher Glove and Intended Location, part 1 of 3

When a catcher holds his glove down and inside, what does that mean? It probably means he wants the pitch inside, and probably low. But how does a catcher call for a pitch high and inside? As we know, the catcher is not going to hold the glove at his face.

The glove is really a reference point. And so, we have to try to infer the intended location based on the reference point. Can we do that? Yes.

We have the location of the catcher's left wrist (all catchers catch with their left hand) throughout the pitcher's delivery. So, what do I do with this information?

Well, I combine this information with the actual pitch location of every pitch. Those pitches I flag into five locations: high/low, inside/outside, or over the heart of the plate.

That's enough words, let's look at the data (click to embiggen). I limit the data for this presentation for RHH v RHP and with 4-seam fastballs, on the idea that the catchers should setup similarly.

The data is captured at 30 frames per second. So, this data is from 2 seconds prior to pitch release to 1 second after pitch release. That's why you see the scale as -60 to +30.

Let's start on top with the orange line, which is how many inches the left wrist is behind the backtip of home plate. Our first interesting finding is that when the catcher is expecting a high pitch compared to low pitch that his glove will be behind the plate by about 2 to 3 inches more. In other words, his glove is 2 to 3 inches closer to himself, when the pitch is expected to be high.

How about the height of his glove? If you look at the final catch point, which is between frames 10 and 20, pretty close to frame 15, the high ball is caught when his wrists are almost 36inches (almost 3 feet) above the ground. The low ball is caught with his wrist about 18 inches above the ground. Now, where were his wrists before the pitch is thrown? If we look at about 10 frames (one third of a second) prior to pitch release, we can see that the wrist is about 2-3 inches higher when the pitch comes in high, as opposed to coming in low.

So, let's stop there for a moment. These are pitches where the final location is about 18 inches apart, and yet the wrist is only 2-3 inches of difference. This makes it pretty clear that the glove is purely a reference point and not a final target. The catcher is just nudging his glove slightly, 2 to 3 inches, in order to get a pitch to have an 18 inch gap up/down. Even if the final location is exaggerated from its intended location, we're still talking about a large multiplier effect here. In other words, it's really hard visually to see if a catcher is indeed calling for a high pitch.

Finally, how about side to side? Here we see about 3 inches of difference. The negative number means it's more inside. So, a high pitch will have the glove closer to the plate, and a low pitch will have the glove closer to the batter, all that by 3 inches of magnitude.

All in all, 2 to 3 inches of difference in each of the three dimensions gives us a total of 4 to 5 inches total. The high pitch has the glove further behind the plate, higher above the ground, and away from the batter.  So if you are going to try to remember this, use the catcher's left knee and his chin as reference points.  Low inside pitches means the glove moves toward the left knee, while a high inside pitch means the glove moves toward the chin.

Next time, I'll look at outside pitches, and how the catcher is setup for pitches high/low.