Digital Love: Why ZiPS Thinks Lucas Giolito is Top of the Charts

In the 2021 ZiPS projections that are live on this very website, Lucas Giolito is projected with the most WAR of any pitcher in baseball. If my social media is any indication, this projection is, so far at least, the source for the most joy and the most consternation. What is it about Chicago’s young ace that gives him such an aggressively optimistic projection?

One of the common complaints you see from readers about projections is that they don’t go out on a limb very often. To me, this makes perfect sense: when talking about the mean projections, massive performance changes should rarely be the player’s typical expectation. Think back on José Bautista back in 2010. At the time, Joey Bats was a player pushing 30 who had hit .238/.329/.400 in the majors in more than 2,000 plate appearances for five major league teams. As we now know, his destiny was to explode on the scene, slugging .617 for the Blue Jays, resulting in the first of his eventual six All-Star appearances. But that doesn’t mean that his baseline projection going into 2010 should have reflected that result; that unlikely things happen doesn’t mean that they weren’t unlikely.

Projections do go out on a limb, but in a conservative sort of way. One of the more notable examples in recent years is the 2019 ZiPS projection for Shane Bieber. With a 4.55 career ERA (but a 3.23 FIP!) in just 114 2/3 major league innings entering the season, ZiPS gave Bieber an optimistic projection as the 14th most valuable pitcher in baseball with a 3.71 ERA over 187 innings for 3.8 WAR. That was enough to put him just behind Clayton Kershaw and ahead of notables such as Zack Greinke, Noah Syndergaard, Stephen Strasburg, and Patrick Corbin. Not only did Bieber meet this projection, but he also exceeded it, finishing eighth in WAR among pitchers at 5.6.

But why did ZiPS love the Beebs so much? It wasn’t one factor. Instead, it was an accumulation of smaller positive factors that significantly outnumbered the negative ones. Bieber was only 24. He had a record in the minors and majors that suggested he could avoid lofty gopher ball totals. His BABIP in his rookie year was extremely high. From his quality-of-contact data, ZiPS thought that batters “should have” hit .252 and slugged .415 against him in 2018 when the actual numbers were .285 and .467. And so on.

It’s the same thing for Giolito entering the 2021 season. No, he isn’t in the same position as Bieber was entering 2019, given that he’s already received Cy Young votes in two seasons. But it does take something special to get ranked No. 1 with a bullet. His top-notch projection doesn’t mean that it’s going to happen, only that it’s more likely to occur than the downside scenarios. And the latter do exist: ZiPS projects a 15% chance that Giolito will be worse than a league-average starter and about a 7% chance he’ll have an ERA on the wrong side of five, both things that would have a very negative effect on Chicago’s 2021 fate.

So what are some of the reasons for this digital love?

Lucas Giolito is Still Relatively Young

Pitchers don’t have a typical age curve, but it’s still preferable to be in your twenties than in your thirties. Like Bieber, the height of Giolito’s ceiling remains an unknown. Both Gerrit Cole and Jacob deGrom are amazing pitchers, but after a few more years in the majors, there’s less uncertainty about their remaining upside. Superstars in their mid-20s, on the other hand, frequently have another gear or two remaining. Among Giolito’s top comparables were a multitude of youngish pitchers who were already stars and did have such performance bumps remaining: Greg Maddux, Jose Rijo, Dave Stieb, Brandon Webb, and so on.

Of the top 50 most comparable pitchers in Giolito’s cohort, 32 of them beat their baseline performance estimates over the following three seasons — an astounding rate of success given how attrition claims pitchers. For Cole, that number is only 23; for deGrom, 26; and for Max Scherzer, 19.

Lucas Giolito is Well-Suited for his Home Park

Home run rates for pitchers are volatile, but they’re not random. Giolito fares well in velocity and barrel-based numbers and was in the top-tier in most of these measures in 2020. Among the pitchers projected in the top 10 overall in ZiPS, only Luis Castillo consistently beat him. And this is especially important because of the characteristics of the park. Guaranteed Rate Field (that name still makes me cringe) is a bit of an unusual bird, a homer-friendly park that tends to be neutral overall. For a pitcher with an elite ability to avoid batters crushing his pitches, this provides an opportunity to squeeze out a little more value. In other words, while Guaranteed Rate is a neutral park for everyone, Giolito’s homer-avoiding tendency makes it a de facto pitchers’ park for him. This one of the reasons ZiPS liked Dallas Keuchel’s chances at a bounceback season in 2020 and continues to think he’ll be very productive for the Sox. Were this a neutral park, Giolito would lose just enough in his projection to drop him to third in the league in WAR.

Lucas Giolito Left Some Strikeouts on the Table

At a 33.7% strikeout rate, Giolito certainly wasn’t struggling to punch out batters. But from the across-the-board improvement in his contact numbers in 2020, ZiPS thinks that he should have seen a larger bump in his strikeout rate from 2019’s 32.3% rate.

As part of its model for calculating baseline expectations, ZiPS has a measurement that I’ve dubbed zSO. (The Z stands for ZiPS, as you may have guessed.) Using contact data, velocity numbers, and the like, ZiPS makes an estimate from how many strikeouts a pitcher “should” have ended up with. It’s not a number I pulled out of my hat but one used as part of the model because it has more predictive value than actual strikeouts. Going back to 2002, if all you knew about a pitcher was his strikeout rate and his zSO rate, you’d have predicted the following year’s strikeout rate most accurately with a mix that was 82% zSO and 18% actual.

ZiPS Strikeout Underachievers (min. 500 TBF)
Pitcher Year Actual K% zSO% Difference Following Season
Francisco Liriano 2011 19.0% 24.4% 5.4% 24.1%
Mike Pelfrey 2016 10.4% 15.6% 5.2% 14.5%
Martín Pérez 2013 15.9% 21.1% 5.2% 16.9%
Martín Pérez 2017 13.1% 18.2% 5.1% 18.3%
Luis Castillo 2018 23.3% 28.3% 5.0% 28.9%
Jeff Fassero 2004 11.8% 16.8% 5.0% 15.6%
CC Sabathia 2008 24.5% 29.5% 5.0% 21.0%
Jeremy Hellickson 2011 15.1% 20.0% 4.9% 16.7%
Jason Vargas 2017 17.7% 22.6% 4.9% 20.8%
Craig Stammen 2010 15.1% 20.0% 4.9% 31.6%
John Smoltz 2007 23.1% 27.7% 4.6% 30.8%
Kelvim Escobar 2006 18.6% 23.1% 4.5% 19.7%
Kevin Correia 2008 12.8% 17.2% 4.4% 17.1%
Jon Lieber 2004 13.6% 17.8% 4.2% 16.3%
Kyle Gibson 2017 17.5% 21.6% 4.1% 21.7%


ZiPS Strikeout Overachievers (min. 500 TBF)
Pitcher Year Actual K% zSO% Difference Following Season
JA Happ 2018 26.3% 19.7% -6.6% 20.6%
Stephen Strasburg 2016 30.6% 24.0% -6.6% 29.1%
Erik Bedard 2007 30.2% 23.6% -6.6% 20.7%
Lance Lynn 2013 23.1% 16.7% -6.4% 20.9%
Zack Greinke 2011 28.1% 22.5% -5.6% 23.0%
Tanner Roark 2019 21.9% 16.3% -5.6% 18.6%
Mike Fiers 2012 25.0% 19.6% -5.4% 14.6%
Mike Mussina 2003 22.8% 17.5% -5.3% 18.9%
José Quintana 2017 26.2% 20.9% -5.3% 21.4%
Tim Lincecum 2009 28.8% 23.7% -5.1% 25.8%
Eduardo Rodriguez 2018 26.4% 21.5% -4.9% 24.8%
Gerrit Cole 2019 39.9% 35.0% -4.9% 32.6%
Rick Porcello 2018 23.5% 18.7% -4.8% 18.6%
Yovani Gallardo 2012 23.7% 19.0% -4.7% 18.6%
Jon Lester 2019 21.6% 16.9% -4.7% 15.8%

Looking at the top 15, while zSO is far from infallible — all models are wrong, but some are useful — it had a solid record at identifying the strikeout outliers correctly. So what about the 2020 season? There’s a lower minimum batters faced here (200 batters faced) because of the short season, so you’ll see some larger-than-typical variations between actual strikeout rate and zSO.

2020 ZiPS Strikeout Underachievers
Pitcher Actual K Rate zSO Rate Difference
Ryan Yarbrough 18.8% 25.6% 6.8%
Dylan Cease 17.3% 23.8% 6.5%
Tyler Anderson 15.8% 22.1% 6.4%
Julio Urias 20.1% 24.8% 4.7%
Alex Cobb 16.8% 21.4% 4.6%
Alex Young 19.1% 23.0% 3.9%
David Peterson 19.5% 23.4% 3.9%
German Marquez 21.2% 24.9% 3.6%
Anibal Sanchez 17.6% 21.1% 3.5%
Tanner Roark 18.6% 21.9% 3.3%
Zack Wheeler 18.4% 21.6% 3.2%
Jesus Luzardo 23.8% 27.0% 3.2%
Brett Anderson 15.8% 19.0% 3.2%
Antonio Senzatela 13.5% 16.5% 3.0%
Randy Dobnak 13.5% 16.5% 3.0%


2020 ZiPS Strikeout Overachievers
Pitcher Actual K Rate zSO Rate Difference
Trevor Bauer 36.0% 26.1% -9.9%
Shane Bieber 41.1% 31.9% -9.2%
Tyler Glasnow 38.2% 30.4% -7.8%
Cristian Javier 25.2% 17.5% -7.7%
Rick Porcello 20.7% 13.1% -7.6%
Zach Eflin 28.6% 21.8% -6.8%
Corbin Burnes 36.7% 30.4% -6.2%
Marco Gonzales 23.1% 17.6% -5.5%
Taijuan Walker 22.2% 17.2% -5.1%
Hyun-Jin Ryu 26.2% 21.3% -4.8%
Aaron Nola 33.2% 28.4% -4.8%
Kevin Gausman 32.2% 27.8% -4.4%
Framber Valdez 26.4% 22.3% -4.1%
Johnny Cueto 20.2% 16.1% -4.1%
Sonny Gray 30.6% 26.5% -4.1%

No, Giolito doesn’t make the top 15 of underachievers, but he’s close. Compared to his 33.7% strikeout rate, ZiPS thought he “should have” been at 35.7. And that’s unusual, as leaders in anything in baseball are more likely to have overachieved than underachieved. Of the top 20 strikeout pitchers in 2020, ZiPS thinks that only four pitchers actually underachieved: deGrom (0.2%), Tyler Mahle (0.3%), Castillo (0.6%), and Giolito (2.0%).

In summation, ZiPS sees Giolito as a nearly perfect storm of awesomeness and one of the top Cy Young contenders in the American League. With Cleveland reeling, the White Sox have an excellent shot at taking the division and going deep into the playoffs. If the White Sox raise a world championship banner in 2021, the right arm of Giolito will likely be responsible for a great deal of the hoisting.

Dan Szymborski is a senior writer for FanGraphs and the developer of the ZiPS projection system. He was a writer for from 2010-2018, a regular guest on a number of radio shows and podcasts, and a voting BBWAA member. He also maintains a terrible Twitter account at @DSzymborski.

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3 years ago

I would be fascinated to see some of the volatility in these top pitchers’ projections. Like, for established stars like Scherzer, deGrom, Cole, etc. who don’t have that “extra gear,” are their 10th and 90th percentile projections closer together than up-and-comers? For example, if Giolito has a 7% chance of an ERA of 5.00+, what are the chances of deGrom putting up a 5.00+ ERA?

3 years ago

0. My final answer.