Statcast: toy, or tool?

That’s a misleading headline!

Because of course the world’s not binary and Statcast is both a toy and a tool. Depending.

Which comes to mind upon reading MLB.com writer Mike Petriello’s piece on three Statcast "lessons" from the technology’s first (public) season.

Those three lessons:

1. Pitch velocity doesn’t lead to exit velocity

2. Exit velocity can be used to track hitters’ health

3. Spin rate can tell us a lot about fastballs

Well, yes. To all three. But I’m still not sure how useful any of this is. Actually.

Yes, it’s long been said that pitcher’s actually supply a lot of a hitter’s power: throw it 100, and it’ll come back 120. And it turns out that while this certainly can happen, it’s not the usual result. Probably because it’s more difficult to square up a pitch that’s difficult to see, and exit velocity is all about squaring.

Does this help us evaluate players, though? Not that I can tell.

Using exit velocity to "track" a hitter’s health? Same thing. The example is Ryan Zimmerman, whose exit velocity was terrible before he went on the DL with a foot injury, and excellent after he came off the DL six weeks later. But was his injury a big secret? If so, I suppose his exit velocity might have been useful to fantasy-baseball owners wondering about Zimmerman. But even that presumes that injuries are the usual explanation for poor exit velocity. If you’re the Nationals and you have to find out Zimmerman’s hurt by looking at Statcast data, it’s too late.

Finally, the example for spin rate is Nathan Eovaldi, who throws exceptionally hard but doesn’t actually have great success with his fastball. Why? Because his fastball’s relatively straight, probably because the spin rate on that pitch is neither high nor low. But, again, did anyone need spin rate to realize that Eovaldi’s fastball was straight?

The trick is going from descriptive to prescriptive; that is, maybe knowing why Eovaldi’s fastball is straight will help him make it less straight. Maybe keeping a close eye on a hitter’s exit velocity will lead to earlier questions about his health, or his swing.

But we’re still waiting for the Holy Grail, comprehensive data that will tell us who gets the best jumps on the bases and in the field, and who takes the best routes from base to base and in pursuit of batted balls.

So far, we’re getting some nifty little baseball lessons. I hope we’ll be excused for being impatient for the big ones.