The Stat That Will Revolutionize Baseball: Introducing UVI

It has since been found that a pitcher can also control their groundball rate, and that groundballs have a different BABIP than flies.

So first, from the variables above, we need to figure out how many plate appearances there were against the pitcher. Simply add 3*IP to the hits, walks, and HBP for that.

Then, we can break down the plate appearances into definite-outcome PA's and indefinite-outcome PAs. To do this, just subtract Ks, BBs, HRs and HBP.

For reference, we'll use Erik Bedard's 2007 line. Bedard faced 749 batters last year; he K'd 221, walked 57, gave up 19 HR, and hit 5. Therefore, Bedard had 302 plate appearances that he controlled the outcome of, and 447 that he did not.

Next, take the indefine-outcome plate appearances and multiply them by the pitcher's groundball percentage. Now, you have split it into grounders and non-grounders.

To continue with the Bedard example, his 49.8 GB% gives him 232 grounders and 235 non-grounders.

A grounder has a BABIP of .251 (Trust me, I researched this to death) and about eight percent of grounders go for extra bases. When you factor in triples to the equation, you get something along the lines of 1.095 bases per groundball hit. Multiply that by the BABIP of .251 and it comes out to .275 bases per grounder.

Thus, Bedard should have allowed .275*232, or 64, bases on grounders last year. This would come on .251*232 = 58 hits. The other 174 hits should have gone for outs.

Flies are much trickier, and caused me a ton of trouble, mainly due to the fact that all are not created equal. Liners, high flies, and popups are all dramatically different. However, I'll spare you the story of my trials and tribulations with flies and simply tell you how to get to the UVI.

First, batters hit .3606 on flies, including homers. So take .3606*the flies to see how many flyball hits the pitcher should allow.

In Bedard's case, .3606*235 = 84 hits. Then, subtract the homers allowed, and multiply the remaining number by 1.394, which, according to my calculations (that is the only time in my life I will ever be able to say "according to my calculations"), is the average number of bases on inside-the-park non-groundball hits.

In Bedard's case, he allows 65 non-homer hits on flies, so 65*1.394 = 91 bases on flies.

Got all that?

Thank God I made a spreadsheet to do all this.

OK, now we can finally get somewhere. Add walks, HBP, and 4*HR to the expected groundball and flyball bases (the 64 and 91 in the Bedard example), and you have your expected total bases allowed. Divide that by the plate appearances, and you have UVI!

Bedard's comes out to .391.

To get expected hits allowed: Just add together the groundball hits and flyball hits (the 58 and 84 in the Bedard example).

To get expected IP: (PA's - BB - HBP - H)/3

Expected WHIP: The formula is in the name, guys.

Expected ERA: I just figured four bases to an earned run, and it works surprisingly well. 

Getting the AVG, OBP, SLG, and OPS from here is easy enough that I won't explain it. If you need help just ask.

Second and Third-order Pitching UVI 

The only thing a park really affects that a pitcher can really control is the homers, so just divide 1000 by the park factor and multiply by the homer total. Then just rerun the stats again.

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