xBB% and Potential Pitcher Walk Rate Regressers
Three years ago, I introduced the best pitcher expected walk percentage formula yet. The formula uses a pair of strike type rates found at Baseball-Reference.com, including a pitcher’s in-play strike percentages, as well as his overall rate of strikes thrown. The beauty of the equation is that it uses components that stabilize quickly, as the rates are per pitch, rather than per inning or per batter. The equation isn’t nearly as strong as my xK% one, as it’s clearly missing sequencing, which may or may not be a consistent skill. But it’s pretty darn good and the best we have at the moment.
I calculated the xBB% marks for all qualified starting pitchers, compared it to their xBB% marks, and sorted. Yesterday, I discussed the group of starters with the most significant potential for improvement in their walk rates. Today, let’s discuss those with the most significant potential for regression as suggested by xBB%.
| Name | SIERA | BB% | xBB% | Diff |
| Taijuan Walker | 3.05 | 2.3% | 7.8% | -5.5% |
| Jake Odorizzi | 3.80 | 4.9% | 9.6% | -4.7% |
| Luis Severino | 3.67 | 4.3% | 8.1% | -3.8% |
| Mike Fiers | 3.80 | 2.8% | 6.6% | -3.8% |
| Jose Quintana | 3.38 | 5.1% | 8.3% | -3.2% |
| Tyler Chatwood | 3.84 | 5.3% | 8.4% | -3.1% |
| Rick Porcello | 3.09 | 5.1% | 8.0% | -2.9% |
| Josh Tomlin | 4.03 | 1.7% | 4.5% | -2.8% |
| Jerad Eickhoff | 3.45 | 4.6% | 7.2% | -2.6% |
| Chris Sale | 3.31 | 5.3% | 7.9% | -2.6% |
| Collin McHugh | 4.14 | 5.1% | 7.5% | -2.4% |
| Matt Moore | 3.49 | 6.5% | 8.9% | -2.4% |
I like Taijuan Walker and this may very well end up being his breakout year, but it’s probably going to be because of the ground ball rate surge and a simple reversal in fortune. His strikeout rate is identical and xBB% suggests his walk rate should actually be higher than last year. There’s an easy story here of the hyped young starter who disappointed last year and is putting it all together this year. That makes him a great candidate to sell high on, though your potential return will obviously decide whether it’s worth pulling the trigger.
What happens when your strike percentage falls by two percentage points? You shave one a half points off your walk rate, of course! Everyone knows that throwing fewer strikes results in better control, right? Well, not exactly, but that’s what has happened for Jake Odorizzi. His underlying skills are almost identical to last year, save for the improved walk rate. But that is in no way supported by his strike rate. Expect that 3.10 ERA to rise.
If it wasn’t enough that Luis Severino has an ERA over 6.00, he should be allowing even more base runners! He’s getting bitten by the luck dragons on all three fronts, which could either mean he’s simply not Major League material at the moment, or he’s a super buy low. I would be more confident if he was generating more whiffs. I’ll still buy in deep mixed and AL-Only leagues, but would shy away in shallower formats.
Despite Mike Fiers‘ appearance here, I’ll be one annoyed owner (in two leagues!) if he’s the one to head to the bullpen upon Lance McCullers‘ return from the disabled list. After last night’s start and Scott Feldman following Fiers in relief, it would seem he’s going to stick in the rotation.
Jose Quintana’s appearance marks just another reason why I’m not so high on him and he remained stagnant in my latest tiers update. He’s doing nothing differently this year than in the past, aside from throwing fewer strikes, inducing fewer ground balls, and allowing more line drives and hard contact. In fact, he actually seems like a worse pitcher! If anyone in your league feels the opposite way and you’re lucky enough to be an owner, take advantage.
It might not take much longer for Chris Sale and the White Sox to realize this supposed pitch to contact strategy is not going to pay off. He’s throwing fewer strikes and getting fewer swings and misses. How can that possibly sound like a good idea?
Even given Matt Moore’s appearance here, I’m rather bullish on his prospects. That xBB% is still much improved from his two full seasons back in 2012 and 2013, while his fastball velocity is at its highest since 2012. He’s getting hurt by an inflated HR/FB rate, which has in turn suppressed his LOB%. It’s masking an excellent skill set that represents a strong rebound to healthier days. He’s not going to throw a whole lot of innings, but he should be very good when on the mound. He’s the only true strong buy on this list.
Mike Podhorzer is the founder of ProjectingX IQ, an advanced fantasy baseball analytics platform that transforms projection data and in-season performance signals into actionable intelligence. He is the 2015 Fantasy Sports Writers Association Baseball Writer of the Year and three-time Tout Wars champion. He is the author of the eBook Projecting X 2.0: How to Forecast Baseball Player Performance, which teaches you how to project players yourself. Follow Mike on X@MikePodhorzer and contact him via email.
Did you write this before or after Matt Moore’s rough start last night? Of course one start shouldn’t change your opinion too much, but his LOB% is now 72% and BABIP at .310…HR/FB still a little high.
3 of his last 4 starts have been poor. I’ve got him in a weekly-moves league (no bench), but if Sunday goes poorly, I’m cutting.
Probably during his start, but hadn’t checked any scores before writing it. Also using stats through Sunday, so last night’s stats wouldn’t have been included. It obviously was a negative though, kind of curious how that affected his xBB%.
I have Porcello and Quintana. Been thinking about packaging one with Madson or Jeffress for a closer upgrade but had been thinking Jose was too valuable? Who do you think each package could net back?
I don’t bother to speculate how your leaguemates value players, but given Quintana’s strong start, I have to imagine you could get a strong closer in return. Find an owner that has an extra one to make negotiations easier, since owners typically don’t want to leave themselves with just one closer or with none.
Given Eickhoff’s continued breakout from last season, do you think his potential walk rate regression will keep him from getting closer to his current FIP of 3.29 and XFip of 3.45 this season?
Yeah, without some good fortune, I don’t think he has the skills for an ERA that low. I think the Steamer RoS projection is fair, though I’d bet on a bit better, maybe in the 3.60-3.70 range.
My question would be what, if any, effect does run support have on walk rate? Quintana is well documented to have had little offensive support last year – a fact that made him a sleeper on many lists. Does walk rate go up with more sun support? Down, as the pitcher is trying to be less pitch perfect?
If I were looking to figure out why these players are anomalies this year that would be where I would start. Applies to both TB players, CWS players, possibly Fiers (Mil to Hou)?
I’ve never heard of this before and have never seen this tested. You don’t know when or if your team is going to score, so how does that theory possibly work? Unless the pitcher has a crystal ball, I’d imagine they would prefer not to walk opposing batters!
What if they have already scored? Do pitchers walk rates increase with a 1 run lead? 2,3? I have seen enough baseball to see, anecdotally, that pitchers pitching in tie games can be a little safer with their pitches, leading to more walks, then again I lived through the Daniel Cabrera years. It was hypothesis based entirely around seeing the list of pitchers names and not any of the underlying numbers.
Based on this calculations, who are some good pitchers to target with high BB% but low xBB%? If there is already an article sorry for the duplication.
Check the link to yesterday’s article.
Past BB% is more highly correlated to future BB% than xBB% is. Do not use xBB% to try and find targets. It is an explanatory variable.
It might be useful for you and Cameron to parse what you’re saying about Quintana: http://www.fangraphs.com/blogs/the-white-sox-have-two-aces/
It’s not a contradiction for him to say he’s “throwing more strikes” with his fastball, and for you to say he’s “throwing fewer strikes,” but I’d like to hear how both of these are true. Is he fewing much fewer strikers with everything but the fastball? Are you unswayed by Cameron? If so, why?
throwing*, rather than “fewing.” Though as far as made-up words go, I like that one.
We’re looking at different metrics. Cameron is referring to Quintana’s four-seam Zone% on our PITCHf/x page, which is indeed up and above 60% for the first time in his career. But it doesn’t seem to match with his overall strike percentage, since all his pitches have a higher Zone% this year, yet his strike percentage is down.
Zone% only cares about pitches inside the zone, while strike percentage includes any pitch that results in a strike. His O-Swing% is at its lowest mark since 2012, so that may be the key. Throwing more in-zone strikes, but his ability to generate swings outside the zone has decreased.
Any thoughts on Quintana’s FT usage? F/X has him nearly tripling his FT% compared to last year, coming equally from his 4-seamer and curveball. If he’s increased his Zone% and used his FT to do it along with the velocities on his fastballs up more than half a tick as well, seems like there’s something a little more going on there?
Then again his GB% is down and his FB% is up, which seems opposite of what should happen with increased FT usage…maybe that comes from his decrease in CB%?