In-Season Batter Regression Tool Updated

click to enlarge

Earlier this year I released a tool that allows you to quickly calculate what a batter's offensive line might look like if they were sporting the same BABIP and HR/FB this year as their 3-year averages. 

The tool isn't a competitor to ZiPS or any other projection tool, rather it is a quick way to get a sense of the impact BABIP and HR/FB is having on a player's performance. It is more of a diagnostic than a predictor. Seeing a player with a huge gap between actual and regressed wOBA should be cause for further investigation.

The tool now sports a custom regression calculator. Here, you can input whatever BABIP and HR/FB ratio you like and see the impact on a hitter's line.

Why add this feature?

The current regression tool uses 3-year averages of BABIP and HR/FB. One potential issue is that some batters may not be represented in the tool. Similarly, for younger players that may only have one year under their belt one might want to come up with their own expected BABIP and HR/FB for them in order to get a sense of how these hitters should be performing.

The example in the screen shot above shows what Adrian Gonzalez might be expected to hit if we gave him a BABIP of only .280 and kept his HR/FB the same as this year. Gonzo currently sports a .382 BABIP, over 60 points above his career average. Doing so reduces his wOBA from above .400 to barely .350.

If we give Gonzalez his career average of .321 BABIP and 17% HR/FB his wOBA zooms to .380.

What about a younger player like Austin Jackson, he of the ridiculous .394 BABIP last year?

Since we only have a year's worth of data to go on, the regression calculator gives Jackson a potential .333 wOBA, a 37 point boost from his actual. But this is based on a .396 BABIP and 3.3% HR/FB from his only year in the majors.

Let's assume his HR/FB isn't that low and his BABIP is not that high. Let's give him the benefit of the doubt and say he's truly a .330 BABIP hitter with a 7% HR/FB ratio. 

click to enlarge

Even with these assumptions Jackson should likely only be having a .311 wOBA, well below league average.

So that's the latest update. Feel free to play around with the tool, just be sure to only alter those cells filled in green with white font.

Once again, here's a link to it.