Revisiting Neil Walker’s plate discipline

Neil Walker - ZumaPress

Last night, Nate Rose of Stealing First Base took my recent article regarding Neil Walker and began digging deeper. He went to FanGraphs and took a look at Walker’s plate discipline numbers, wondering whether we should expect his walk rate to improve. Nate noted that Walker does not chase out of the zone all that much, and my interest was piqued. First, a brief excerpt from Nate’s post.

Something I’m interested in looking at, though, is whether there’s any hope that Walker will start drawing walks again. Looking at his plate discipline data at FanGraphs, I think there’s reason to believe that the walks will come. According to FanGraphs, Walker swings at pitches out of the strike zone 29.1% of the time. That sounds like a lot, but the league average is 28.9%, so there’s only a 0.2% difference there. As far as making contact with those outside pitches, he does it 73.5% of the time, presumably fouling off most of those to keep the AB going. The league average is 66.5%. And finally, his swinging strike percentage is 8% as compared to the league average of 8.4%.

This post reminded me of some excellent work done in March by Jeff Zimmerman at Beyond the Box Score. Jeff created a formula that estimates walk and strikeout rate based on these plate discipline stats.

For a while, I have wondered if pitch data could be used to estimate a player’s walk and strikeout rates. At, they display the percentage rate for pitches swung at and hit inside and outside the strike zone for each player (O-Swing%, Z-Swing%, O-Contact%, Z-Contact%). Using multiple variate regression, I took the 4 variables (outside swing and miss, outside contact, strike zone swing and miss, strike zone contact) and compared them to strikeout and walk percentages.

With Jeff’s help, we can determine whether Walker’s reasonable plate discipline stats should lead to stronger walk and strikeout rates that could soften the blow when his BABIP inevitably falls. Here are Walker’s numbers, going into the Bucs’ Thursday afternoon game.


O-Swing% Z-Swing% O-Contact% Z-Contact%
29.40% 66.40% 72.40% 87.60%


After plugging those into Jeff’s formulas, we come up with the following expected rates.


BB% K%
Actual 5.30% 21.90%
Adjusted 6.67% 17.24%


That walk percentage is still below average, but it is a fairly solid improvement. Just as important, the decreased number of strikeouts should help keep his average from falling off too far due to an expected BABIP regression. Simply adjusting based on Walker’s xBABIP, as I did in my first article, gives us a line of .264/.303/.415. When I follow that up by adjusting for our new and improved K/BB rates, that climbs back up to a more respectable .274/.326/.425. These slash stats clearly are not as exciting as his actual .307/.343/.458 line, but they are a bit less foreboding than the original numbers that I posted earlier in the week.





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