Reviewing The 2017 Starting Pitcher Walk Rate Regressers

Yesterday, I reviewed the 2017 starting pitcher walk rate improvers using my updated xBB% equation. Today, I’ll recap my walk rate regressers, which includes those starting pitchers whose actual walk rates were significantly better than their xBB% marks.

Well gosh, xBB% goes seven for eight! The only miss was on Jose Berrios, a perfect example of how xBB% is not meant to be a projection, even though it works decently as one on the extremes. Obviously, no one would expect Berrios’ walk rate from 2016 of 12.5% to rise even further, even though his xBB% was higher.

Kevin Gausman’s first half was a disaster, but it was really just two months (April and June) of inflated walk rates that ruined his season mark. He’ll be undervalued if owners are looking at his full season stats and forgetting that he rediscovered the magic in the second half.

What happened to Jake Odorizzi’s control?! xBB% thought he was lucky to post just a 7% mark in 2016, but it definitely didn’t see this level of decline coming. He missed time due to hamstring and back injuries, but who knows if those maladies affected his control. I’m sure he’ll bounce back, and he has actually outperformed his xBB% for four straight seasons by a significant degree.

Obviously, no one would expect Jose Berrios to post a walk rate near his 2016 xBB%. He was much better in the minors, and sure enough, his 2017 walk rate dropped back to where his minor league marks sat. I think he’ll be overvalued in 2018, though, as most of his strikeout rate hinged on the success of his four-seamer, rather than any of his secondary pitches. The curve was above average at inducing whiffs, but nowhere near elite, while his changeup was awful. He’ll have to improve those for any strikeout rate upside, and he’s going to keep battling the high fly ball rate that makes him prone to gopheritis (there’s no reason to think he’s capable of another sub-10% HR/FB rate).

Somehow Zach Davies managed a sub-4.00 ERA despite a pathetic strikeout rate and a SIERA approaching 5.00. It’s the sinker that has killed him, as it comes in below 90 mph and generated a measly 2.4% SwStk% this season. However, both his curve and changeup were excellent, so if he ever decided to cut down on those sinkers (probably at the expense of his ground ball rate), his strikeout rate would spike and he might be a bit more interesting for fantasy.

Chris Tillman’s SIERA outperformance skills completely disappeared all at once. He never owned good skills to begin with, and without a low BABIP, he’s worthless.

Gio Gonzalez’s walk rate improvement from 2015 to 2016 was a mirage according to xBB%, and sure enough, his walk rate jumped right back up. He has posted similar strikeout rates the last three seasons, but some amazing BABIP and LOB% luck pushed his ERA below 3.00 for the second time in his career. Pretty crazy considering his fastball velocity also declined by nearly a mile per hour to sit below 90 mph for the first time. Depending on your league, he’ll either be fairly valued or far too expensive.

Carlos Rodon’s walk rate improvement in 2016 appeared to be a complete fluke, and xBB% was correct — Rodon’s walk rate jumped right back up into double digits again. Of course, he battled both a biceps and shoulder injury (which led to surgery), which may very well have affected his control. He’s likely to get a late start to the 2018 season and we can’t be sure how the surgery will affect his performance.

Jameson Taillon posted a minuscule 4.1% walk rate during his 2016 debut, but there was little chance he would come close to repeating. He ended up seeing his walk rate rise far more significantly than anyone predicted, and an insane .352 BABIP combined to fuel a disappointing 2017 performance. I still fail to understand the initial top prospect hype here as his assortment of pitches simply don’t induce swings and misses. His best pitch is his curve, and that has generated SwStk% marks in the low teens, while his four-seamer (his sinker has actually been good) is nothing special and changeup terrible.