In the lab: Checking in on Yainer Diaz

We did this with Cam Smith last time and it seemed like a good feature to move forward with most of the hitters individually. The general idea here is that the basic numbers will say one thing, but the underlying numbers might say something else. For instance, we saw that Smith is making more progress according to the underlying numbers than his basic numbers would say. Is the same thing happening for Diaz?

Unfortunately for Diaz, his injury came at the worst possible time for him. He was beginning to show signs of life as he had his batting average go above .250 before slipping back below slightly. He was hitting for a little more power as well. Were those numbers fool’s gold or were they a precursor of what is to come? Let’s look at the basic numbers.

The Basic numbers

First of all, I threw in a new category this time we have called BABIP (batting average on balls in play). The league average tends to hover around .300, but it is not uncommon for catchers to come in considerably lower than that. They won’t beat out many infield singles, so if you take an odd hit per week out here and there you can see a .270ish average being reasonable.

BABIP is also a function of your contact which we will get to shortly. Essentially, if your catcher is producing a 92 wRC+ you will likely live with that. That is a league wide stat and compares all players in the same bucket. There isn’t a position on the planet where a 68 wRC+ will fetch anything. The same is true for the weighted on base average. Those numbers can be interpreted like OBP but include a slugging element. A .273 mark is abysmal but maybe there are some underlying numbers that will bring us more news.

This biggest problem with Diaz is what I would label as isolated patience. It’s a number that you won’t find on the stats sites, but it gets worked into other numbers like secondary average. It is the difference between OBP and AVG. A .016 isolated patience is ludicrously low. The most patient hitters in the business will be over .100. Add that all up and it doesn’t look good.

Statcast Numbers

Statcast projects what you would likely hit if your rate and quality of contact received average luck. Diaz was unlucky in the power department last season and if he had had normal luck would have been more or less league average according to his expected weighted OBA. I’m sure this gave the Astros some room for optimism. We are not seeing that so far this season.

So far, we dare say that Diaz has been better than what the underlying numbers say he should be. Nearly all of those gains are in the batting average department. Secondary average combines isolated patience, isolated power, and stolen bases to come up with a number that should be similar to batting average. If we look at the expected numbers we see that he has a secondary average barely over .100. That is ridiculously low.

If you read the Smith piece then you know what is coming next. We are looking at why this is happening and then we are looking at what Diaz can do to grow. I think anyone reading this article can answer the second question without the fancy numbers, but it is probably still good to look at how bleak the situation looks. First, let’s look at how statcast arrives at these numbers above.

Quality of contact

League norms are great and necessary nine times out of ten. You don’t need them here. Just look at what happened last year as compared to this year. He has lost more than two MPH on his average contact. The barrel rate is the most alarming. Think of that as how often you hit the sweet spot in golf. Hitting it there doesn’t guarantee success, but you can imagine success being a lot more likely if you do hit it there.

That brings us to the hard hit percentage. A 42.2 percent rate is actually pretty good in comparison with the rest of the league. A 28.7 is clearly not. He is making softer contact. The ball is not coming out hit as hard off his bat as it was before. He is getting jammed or hitting it off the end of the bat more often. All of these add up to the lower statcast numbers that we saw above.

I’m not a hitting coach and I didn’t stay at a Holiday Inn Express last night, but the advice to Diaz is pretty damn simple: stop swinging. We will look at those numbers below, but it should be noted that all of them lead the Astros by a wide margin. He’d shock the world if he stopped swinging at balls and might have the highest walk rate in the league. Let’s see the numbers.

Areas of Growth

These numbers are a testament to the fact that most hitters don’t change all that much. Their results might change if the sample size is small enough. The chase rate is self-explanatory and the highest on the Astros. In fact, it is amongst the highest in the league. I suppose we see some small improvement there so far, but 30 percent tends to be league average. With the walk rate going up league wide, that benchmark might need to be recalibrated. In other words, Diaz might actually come off looking worse.

The swing rates tend to hover around 50 percent league wide. Again, that might be lower with the ABS adjustments. Again, his rate is higher than anyone else on the team. However, the contact rates are excellent and especially so when you consider how few strikes (zone%) that he sees. He is swinging at bad pitches and putting them in play for the most part.

However, what is the quality of that contact? As we saw above it isn’t very good. Pitchers know they don’t have to throw him anything good, so they get him to chase their pitch. Fortunately for Diaz, he is talented enough to make contact, but it is not going to be quality contact. So, the area for growth for Diaz is as easy as it gets. Stop swinging. If he swing percentage went down to 55 percent it would be measurably better and if it went down to 50 percent it would be a revelation.

Putting it all together

It is hard for me to remain completely neutral when it comes to players like Diaz. The analytical mind has an almost allergic reaction to free swingers like Diaz. However, I have to acknowledge the advanced hit tool that it is there. No matter what we say, the future is unwritten. There is always the hope for improvement even if the underlying numbers don’t allow for much of that. The most likely result will be that Diaz will not be a regular catcher beyond this season. That is doubly true when we also look at his defense as we will see in another lab. He has time to fix this, but there is nothing in the current numbers to suggest that he will.