Are foul balls a skill? Do they lead to better outcomes? Should all hitters have a two-strike approach?
These are the kinds of things (among others) that Sam Fuld has been thinking about in the outfield.
Let’s try to answer some of those questions the best we can.
If fouling a ball off was an easily measured skill — if percentage of balls fouled was a good measure of that skill at least — then you’d expect the skill to show through most years. Strikeout rate, for example, is fairly decent at measuring your ability to make contact. Strikeout rate stays fairly stable — you could use shorthand to say that almost 90% of your strikeout rate next year is described by your strikeout this year.
Foul percentage doesn’t work that way. Your foul percentage this year describes about 40% of the variance in your foul percentage next year. That makes foul percentage more unstable than batting average, batting average on balls in play, or your rate of doubles per plate appearance. Brian Roberts was 11th in baseball foul percentage this year, he was barely above average in 2013. So it goes.
Read the rest on Just a Bit Outside.
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Sam Fuld went to Stanford. It all makes sense now.
Eno, “explanation of variance” is R^2 and correlation is R. Also, gotta be careful with putting these correlations in context. The smaller the sample (number of pitches, not the number of players), the smaller the correlation even for the same “skill level” or “spread in skill.” So even if batters had the same spread in skill in terms of fouling off all pitches and 2 strike pitches, 2 strike pitch y-t-y correlation will be much lower simply because the number of 2-strike pitches seen or swung at per batter is much smaller than the number of overall pitches seen or swung at.
Dammit. I sent corrections in. Don’t know why my software doesn’t even report an r, just r2, but it’s on me.
Haha. No prob. So those are all R^2?
Yeah so it’s a decent measure actually. I’d like to re-run with fouls/swing, might get up there with contact rate in terms of year to year stickiness.
Based on the title I thought this was going to be a followup on pitchers w/high foul strike %’s a la Odorizzi 2014 http://www.fangraphs.com/fantasy/should-you-be-buying-jake-odorizzi/
I love the idea of Sam Fuld zoning out in the outfield, musing about these things, and then realizing a liner is on its way over his head. The presser afterwards “So on that hit I was out there thinking about the correlation between two strike counts and…”
Is there a relation between foul ball rate and walk rate? Theoretically, a player who would be able to foul any pitch close to the strike zone would get a walk on every plate appearance.