We have discovered something marvelous! We only need to know four simple measures to predict what a hitter can do: Their walk rate, strikeout rate, home run rate and BABIP.
For weeks now, we’ve been exploring and playing with my initial discovery, and now we’re to the point where I feel comfortable calling it Fielding Independent Batting (FIB) — an homage to Fielding Independent Pitching (FIP), which predates it and partly inspired it.
I have created a final, consummate Google Doc, aptly titled Complete Should Hit (Advanced Predictor!) — as seen above. The document has several tabs, so let me explain:
- —> Fielding Independent Batting: The previous rendition of ShHAP! focused solely on BABIP fluctuations. FIB allows us to calibrate everything. Above, we see the present state of a one Ben Zobrist, titan among men. With FIB, we can choose to calibrate his present season according to his career rates (which I have done above).
If, say, I think his homer rate in 2011 is more accurate than his career rates, then I can adjust that accordingly. If I think he’s been unlucky on the walks this year and could be walking even more through the end of the year, then I can alter that as well. FIB allows us to give a quantitative prediction to changes we expect.
—> ShHAP! BIP: Want to see what a player should hit with just a normalized BABIP? Well, ShHAP! BIP is your man. Unlike ShHAP! 1.0, “BIP” only requires a present wRC+, a present BABIP, and a future or expected BABIP. The results are the same, but the process is simplified.
—> ShHAP! Walk: The same with BIP, “Walk” allows us to simply answer the question: “What difference does Ben Zobrist’s career and present BB% make on his wRC+?”
—> ShHAP! Punch: Punch helps us answer the question: “What if Zobrist was punching out (K%) 1.5% lower (his career rate)?”
—> ShHAP! Homer: With homer, it gets trickier. The formula itself calculates the HR% using home runs and plate appearances — two stats more commonly available than an already-computed HR%. So, as I have done above, we can just put the player’s present and career numbers in; but we can also say crazy things, like: “I believe the 2009 Ben Zobrist was the real one,” and then substitute those — much higher — homer numbers into the formula.
If you think his 2.9% homer rate is incorrect (and given his crazy-bad first two seasons, it may be) then moving it to an arbitrary 3.2% or something is a bit more difficult. Basically, you’ll need to reverse calculate it using maffematix n’such.
So, for 3.2%, you’d put 3.2 homers in the career section and then 100 plate appearances in the corresponding, neighboring career PA box.
Now go! Play with this new FIB toy and tell me what’s wrong, what can be improved, and what surprises you!
NOTE: In order to edit and play with the Google Doc, you will need to make a copy or download your own version from my original.