Prospect Scouting & Stats — Hitter Hit Tool

For the last week and a half, I have looked at prospect scouting power grades and stats. Today, we move along to prospect scouting hit tool grades. While power grades are pretty clearly meant to forecast a prospect’s Major League ISO and/or HR/FB rates, it’s not entirely obvious to me what a Hit grade is meant to tell us.

Is it indicative of underlying skills relating to hitting ability, such as walk/strikeout rates, along with BABIP, or is it more of the ultimate result of those skills, such as batting average and/or on base percentage? From perusing through Kiley McDaniel’s old articles back in 2014 explaining the scouting grades, it seems like OBP is the intent, but I’m not 100% sure. Either way, let’s dive into the correlations between the present and future hit grades with the various underlying hitting talent skills and results.

For clarity on which metrics correlate best, the following tables are sorted by the absolute values of the correlations.

It certainly makes life easier that the order of the absolute value of the correlations is the same for Hit – Present (HP) and Hit – Future (HF).

What’s fascinating to me is that the three of the five metrics correlate more strongly with HF than HP, one of them is essentially the same and doesn’t correlate at all, while the last (BABIP) correlates negatively for HP, but ever-so-slightly positively for HF. That’s weird.

The three metrics (K%, AVG, OBP) correlating more strongly with HF than HP is opposite of my findings when analyzing the power grades, where I learned that the two hitting metrics correlated better with present power than future power. My guess is because power, in its current form, translates better to MLB, whereas a prospect’s strikeout rate, AVG, and OBP, typically get significantly worse in the Majors. So the HF grades matches more with their current minor league metrics, which is where they are expected to rebound back to in the Majors after their results dip during their debut. Do you agree with this explanation or do you think it’s something else?

For both HP and HF, strikeout rate actually correlated best with the grades, and by a dramatic degree. Are you surprised? Was this intended by the grades, simply to tell us a prospect’s strikeout rate potential? I don’t think it was.

Correlating at the next highest degree is batting average. While this ranked second, it’s a rather low correlation, especially with the HP grade. Finally, in third, we find OBP, at less than half the correlation of strikeout rate. If these grades are meant to tell us about a prospect’s OBP potential at the MLB level, then we shouldn’t bother looking at their actual OBP recorded in the minors.

But then I wonder, is the grade suggesting the prospect’s walk rate, strikeout rate, or BABIP change significantly upon promotion to the Majors? Because those are the main drivers of OBP (obviously home runs as well, but that has its own grade). And what about a prospect would make one think his walk rate, strikeout rate, or BABIP skills are going to be different in the Majors than he has currently posted in the minors?

Last, we find BABIP and walk rate. I used to assume that hit tool grades were really telling us about a prospect’s BABIP skills. Perhaps other sources of grades do, but certainly not the FanGraphs version!

So according to these correlations, there’s no shortcut to guessing the HP grade, as it doesn’t correlate strongly with any of the minor league metrics you would expect it to. For the HF grade, you can just look at a hitter’s minor league strikeout rate. If it’s high, he probably was slapped with a low grade. If it’s low, he was probably slapped with a high grade.

Of course, what’s missing from this analysis is how these prospects actually performed in the Majors, because that’s really what these grades are supposed to tell us. Luckily, Jeff Zimmerman already did the work a couple of years ago.

Unluckily, he concluded that…

Basically, the Hit tool is a useless component to determine hitter value as it’s currently being distributed.

Ouch. Personally, I would rather analyze the components that drive a batter’s hit tool, which are strikeout rate, BABIP, and home run rate (which itself is fueled by strikeout rate, fly ball rate, and HR/FB rate). There are too many independent skills that drive a hitter’s AVG, OBP, or whatever result we’re trying to project with this grade to sum it up in one number.