## Potential BB% Risers Through the Lens of F-Strike%

Although we have done a pretty good job determining what underlying statistics can combine to formulate a strong expected strikeout percentage metric, unfortunately the same cannot be said for a pitcher’s walk percentage. Though one would assume the majority of a pitcher’s control skill would show up in his ability to throw strikes, whether by throwing first pitch strikes or throwing the ball inside the strike zone, that just isn’t the case. But of course that doesn’t mean that this data is useless.

Although we have looked at this before, I figured I would check it out again just as a reminder of what the correlation between F-Strike%/Zone% and BB% is. I used the same data set I have been using recently, which is all starting pitchers who have thrown at least 50 innings from 2003-2012. The R-squared for F-Strike% was 0.4374, while the R-squared for Zone% was a less useful .0794. Though the F-Strike% metric’s R-squared is rather low, it still would likely rank as the biggest factor when projecting a pitcher’s future walk percentage.

Clearly there is more going on that affects a pitcher’s walk percentage than just the ability to throw first pitch strikes. But since we haven’t come up with a strong regression equation yet, the simplest method to determine potential swings in BB% is to just compare a pitcher’s F-Strike% with his BB%. To do this, I just sorted starting pitchers with at least 20 innings pitched by BB% and eyeballed the corresponding F-Strike%. Those with marks well below the pitchers around him with similar BB% are at risk of walking more batters over the rest of the season, assuming all else remains equal.

Also important to note is that the league average BB% among all starting pitchers is 7.4% with a F-Strike% of 60.7%.

Name BB% F-Strike%
Doug Fister 3.4% 57.3%
Kevin Correia 3.8% 58.0%
Aaron Harang 3.8% 59.6%
Ross Detwiler 4.6% 55.1%
Eric Stults 5.0% 59.0%
Mike Leake 5.3% 59.4%
Scott Diamond 5.4% 58.9%
P.J. Walters 5.5% 54.6%
Andrew Cashner 5.5% 57.3%
Wei-Yin Chen 6.4% 56.9%
Tony Cingrani 6.4% 56.7%
Mark Buehrle 6.5% 54.0%
Jered Weaver 6.6% 51.2%
Zack Greinke 6.8% 55.8%
Jordan Lyles 7.2% 56.1%
Justin Grimm 7.2% 56.7%
Mike Pelfrey 7.2% 51.9%

Doug Fister has the sixth lowest walk percentage among all starters with at least 20 innings pitched. Yet, his F-Strike% is both below the league average and at a career low. Hmmmm. Fister has always posted very strong walk rates, but he has done it by throwing first pitch strikes more frequently than the average starter. Not this year. A walk rate that matches that F-Strike% is well above Fister’s current BB%, but it’s hard to believe he will suddenly lose control to the point that he posts a BB% worse than league average the rest of the way. Still, it’s something to keep an eye on.

With a much improved walk percentage and solid ERA to boot, it might be tempting to claim that Andrew Cashner has become a pitcher, transforming from his days as a thrower (I hate that cliché). But if you dig deeper, you realize his F-Strike% is the exact same it has always been, so you have to wonder what’s behind the apparent control improvement. If I didn’t own him in nearly all of my leagues after hyping him so much in the pre-season and didn’t have faith that his raw stuff would lead to a higher strikeout rate moving forward, I would likely call him a sell-high candidate. But it’s hard to jump off the Cashner train now.

With Johnny Cueto returning from the DL, Tony Cingrani is now being shifted to the bullpen. He might get another shot in the rotation later in the season though, which means it’s worth noting that his F-Strike% is rather low. His minor league walk percentages also do not suggest control this good, so you have to expect that BB% to rise. In addition, I just cannot imagine a starter who throws his fastball over 80% of the time maintaining a strikeout rate anywhere near what he has posted. At some point the league is going to adjust and then it will be up to Cingrani to start throwing his secondary pitches more often.

Woah, Jered Weaver‘s F-Strike% has never dipped below 60% over a full season and his worst mark was 59.4% during his rookie year in 2006. He now sports the third worst F-Strike% among all starters with at least 20 innings pitched! Amazingly, it has barely affected his BB%, as it’s only a smidge above his three previous seasons. In three of his five starts this year, his F-Strike% has been below 48%. This is just unheard of for a pitcher who has always exhibited excellent control. It’s hard to continue counting on a guy who has made a living outperforming his expected ERA metrics each season.

Zack Greinke‘s F-Strike% is also at a career low and the first time it has dipped below 59%. His BB% is also up only slightly from previous seasons, so you have to wonder how he could continue limiting the walks while failing to throw first pitch strikes as often. His fastball velocity remains down as well and he has now only exceeded an average of 91.0 mph once all year. Last year, his season average velocity was above 92.0 mph. Like with Weaver (whose velocity is also down), I’m not sure what to make of the two and would be nervous about trying to buy low.

Print This Post

Mike Podhorzer is the 2015 Fantasy Sports Writers Association Baseball Writer of the Year. He produces player projections using his own forecasting system and is the author of the eBook Projecting X 2.0: How to Forecast Baseball Player Performance, which teaches you how to project players yourself. His projections helped him win the inaugural 2013 Tout Wars mixed draft league. He also sells beautiful photos through his online gallery, Pod's Pics. Follow Mike on Twitter @MikePodhorzer and contact him via email.

### 14 Responses to “Potential BB% Risers Through the Lens of F-Strike%”

You can follow any responses to this entry through the RSS 2.0 feed.
1. Mister says:

Has anybody ever looked at the rate at which pitches are fouled off to see if that correlates to BB% at all? I wouldn’t even know where to find such stats. I don’t even know if foul ball percentage is something that pitchers have much control over. However, just from watching baseball the game, it seems like a lot of walks occur after a pitcher has gotten 2 strikes but is then unable to put a batter away because he keeps fouling pitches off. Eventually, the pitcher starts missing the strike zone trying to get a swing and miss, and if the batter lays off then the PA ends in a walk. I would hypothesize that this happens to a pitcher with mediocre stuff. A guy with great stuff would get more whiffs, and thus more Ks and fewer BBs. A guy who is more hittable would eventually give up a ball in play and not get a lot of Ks or BBs. A guy with a mediocre out-pitch that is good enough to not get put in play but not good enough to get whiffed on altogether would get fewer Ks and more BBs. I could be way off here, but I’ve just never seen any work done on foul ball rates either for pitchers or hitters.

• FanGraphs Supporting Member

Yes, I included Foul Strike% in my expected strikeout percentage metric. Unfortunately, it’s only available on Baseball Reference. And they actually do have lots of control, year-to-year correlation was over .50. I think your theory is somewhat reasonable, but I don’t believe it’s true. If you consider the high walk guys, I don’t think they have worse stuff at all. They just have bad control.

However, you did pique my interest, so I’m going to try combining Foul% with these metrics to see if they help.

2. Brandon says:

Fister also has like 15 HPB this year as well. Obviously any 3-x count HBP would’ve been a walk instead so calculating those would be easy. With only 14 unintentional walks on the year, adding another 5 or so wouldn’t be completely insignificant.

3. Walker says:

You mentioned that Cigriani needs to adjust when batters adjust to his fastball-heavy repertoire. The question is: what has taken batters so long? Aren’t most batters sitting on fastballs anyway?

• FanGraphs Supporting Member

Well, you would think, but he has some deception going on with his delivery apparently (this is what I have read/heard). I’m no scout so when watching him, it’s hard for me to spot. But I’m sure it’s making it tougher for hitters to adjust. So it might take them a bit longer than normal, but I have to imagine it will at some point.

• Walker says:

Thanks for the feedback, and keep up the good work!

4. Travis L says:
FanGraphs Supporting Member

Wainwright has a lower BB% than Fister.

• FanGraphs Supporting Member

That’s odd, I have no idea what I was looking at! Fixed now, thanks.

5. esolney33 says:
FanGraphs Supporting Member

Question in case anyone still on this thread – something that has always bothered me about the F-strike analyses. I can see how there would be a connection b/w F-strike % and BB %, but why not a stronger connection b/w overall strike % and BB %? Folks have obviously looked at this and determined there is not, but any idea why? Doesn’t seem to make sense.

• FanGraphs Supporting Member

There is! In the data population I used in the article linked to below, there was a -0.75 correlation between strike % and BB%. http://www.fangraphs.com/fantasy/the-best-pitcher-expected-bb-formula-yet/

• esolney33 says:
FanGraphs Supporting Member

ha, i’m not crazy. thanks.

• esolney33 says:
FanGraphs Supporting Member

This site often uses F-strike % as a peripheral for walks. Why not use overall strike %?

• FanGraphs Supporting Member

Because Strike% is only published on Baseball-Reference. Technically, we could calculate it from the data on here, but obviously it’s a bit easier to use stats displayed on these player pages.

• esolney33 says:
FanGraphs Supporting Member

got it