Which AL Starting Pitchers Are Inducing More In-Zone Whiffs?

As it remains far too early to actually analyze results (like ERA and WHIP), let’s continue discussing the underlying skills driving those results. Those skills are significantly more important when projecting for the future. So let’s find out which American League starting pitchers have improved their in-zone whiff rate the most. In FG metric parlance, that means calculating who has reduce their Z-Contact% by the greatest rate.

AL SP Z-Contact% Improvers
Player 2018 K% 2018 Z-Contact% 2017 Z-Contact% Diff
Tyler Skaggs 25.0% 78.7% 90.2% -11.5%
Mike Fiers 20.4% 74.5% 86.0% -11.5%
Cole Hamels 30.6% 76.5% 86.7% -10.2%
Lance McCullers Jr. 37.4% 80.0% 90.1% -10.1%
Blake Snell 30.6% 77.0% 85.4% -8.4%
Charlie Morton 33.3% 75.3% 83.6% -8.3%
Gerrit Cole 46.8% 77.4% 85.5% -8.1%
Justin Verlander 33.7% 78.3% 85.4% -7.1%
Dylan Bundy 29.8% 78.1% 85.2% -7.1%
Francisco Liriano 20.0% 80.3% 87.3% -7.0%

The unweighted average K% in this group is a whopping 30.8%. So yeah, making hitters miss inside the zone is a good thing!

Who would have guessed that Tyler Skaggs would sit atop this list? He’ll be making another start in a couple of hours after typing this, so it’s likely this mark moves, perhaps dramatically. That Z-Contact% improvements has fueled a spike in SwStk% into double digits for the first time. His velocity is the same as last year and his pitch mix is essentially the same, with one difference — he has swapped out some four-seamers for sinkers. Normally, that wouldn’t increase your whiff rates. However, Skagg’s surge actually is due to his fastball, both his four-seamer and sinker. Both have seen their Z-Contact% marks plummet, especially the sinker. Sinkers rarely generate this kind of whiff rate, and his four-seamer has never been this good. So I’m not buying this surge, even though I own several shares.

Small sample size alert: so Mike Fiers has only made two starts, throwing 11.2 innings. It’s not worth diving very deep here, but it’s funny how he was so horrible during spring training and everyone left him for dead. Now he’s fine. Once again, spring training means nothing.

Cole Hamels pitched earlier in the day as I type this, and he struck out just 14% of the batters he faced. It’s pretty amazing that his whiff rates are where they are considering his fastball velocity is at its lowest mark since 2008. His changeup and cutter had been incredible this year, and have been the drivers of his Z-Contact% reduction, but could he sustain such success with a weaker fastball? I’m not touching him.

Lance McCullers Jr. owns one of the most absurd statistical profiles so far. There’s too much to discuss here, but let’s just say this guy’s a stud. He has thrown his curve even more than before, and he was already throwing it a ridiculous amount. Now that usage percentage has jumped above 50%. Might as well with one of the best pitchers in baseball.

I probably won’t forgive myself all season for not owning any Blake Snell shares. All of his non-fastballs have been elite at generating swings and misses, but the driver of his Z-Contact% improvement this year is actually from his four-seamer. For a guy who averages in the mid-90s with his fastball, you’d figure he would generate more whiffs.

Remember when Charlie Morton was just a generic groundballing Phillies hurler with a poor strikeout rate? Amazingly, he has transformed himself at the tender age of 33. Even more amazing is that his sinker velocity has increased again, notching another new career high. When he debuted, he averaged around 90 mph, and now he’s at 96! That’s CRAAAAAAAAAAZY. Other than the velocity spike, he’s traded some sinkers for four-seamers. That would normally increase whiffs at the expense of grounders, but he’s still inducing nearly 60% grounders!

So we all know the Gerrit Cole story by now, and having moved to the Astros, the team has had him up his breaking ball usage. Both his slider and curve ball are being thrown more frequently, though not excessively so. Those increases have almost solely come at the expense of his sinker. Fewer sinkers could explain his sudden transformation into a fly ball pitcher. Surprisingly, his Z-Contact% actually stinks on his slider, and although his curve and changeup are marginally improved, the real difference is in his four-seamer. Usually, I would guess he’s throwing the ball up in the zone more, which has increased his whiffs and fly ball rate. That hasn’t been the case though, as his vertical pitch location has remained quite consistent since 2013. I’m a fan, obviously, but he’s not this good, and floating him out there to potential trade partners would be an interesting exercise.

After he had been losing velocity and his ERA jumped over 4.00 for the first time in years, we all wondered whether Justin Verlander was done as an elite pitcher. Turns out, he wasn’t. His fastball velocity spiked last season to its highest mark since 2011, and he’s held onto some of those gains so far this year. He’s throwing his slider more instead of his curve, but that’s not the reason for the improved whiff rate. Instead, it’s his four-seamer, but unlike Cole, Verlander’s vertical pitch location is actually at the lowest of his career! So it’s hard to believe this is real.

Dylan Bundy’s slider has been insane. That’s all.

Is the good Francisco Liriano back? His velocity is down and he’s throwing his slider a little more, but there’s some weirdness going on in the plate discipline metrics. While his Z-Contact% is at its lowest rate since 2006, his O-Contact% has completely offset it as it has surged to a career high. Since his SwStk% is at a career low, it looks like some implosions are imminent.

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. Follow Mike on Twitter @MikePodhorzer and contact him via email.

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Brad Johnson

Seeing four Astros on the list makes me wonder how their opponents perform against pitches in the zone.


Unfortunetly the Splits leaderboard does not show Plate Discipline otherwise you could take a look at their opponents for this year and see how they perfrom against the rest of the league ex-Astros. As is it they have played 13 of thier 19 games against the bottom 3 in Z-Contact, how much is from facing the Stros is hard to pull out, especially the Rangers has it’s been so overweighted.
Rangers 7 games, 82.3% Z-Contact, 28th in the league
Orioles 3 games 81.5% Z-Contact 29th
Padres 3 games 81.2% Z-Contact 30th
Twins 3 games 84.9% Z-Contract 15th
Mariners 3 games 88.7% Z-Contact 1st