There are many ways to succeed as an MLB starting pitcher. One way is to strike a lot of hitters out without a lot of walks. This conventional method has created dominant pitchers in Clayton Kershaw, Max Scherzer and Chris Sale. Another way is the Kyle Hendricks special: generating infield fly balls and limiting hard contact. But, there is also the Dallas Keuchel model: getting a ton of ground balls.
Before this year, Diamondbacks starter Zack Godley did not excel in either of the first two categories; he had a below-average strikeout-to-walk ratio and a poor infield fly ball rate. His ground ball rate, of 53.8 percent, was good, at 9.5 percentage points above the Major League average.
Godley’s 2016 season was nothing stellar. Appearing in 27 games and making nine starts, he pitched 74 2⁄3 innings. His 6.39 ERA was ugly, but his 4.97 FIP and 4.20 xFIP marks suggested he was a much better pitcher than his run prevention numbers showed. As a result, Godley’s season wasn’t disastrous in the WAR department, either; FanGraphs pegged him at 0.0 fWAR, an average replacement-level player.
In 2017, though, Godley has apparently flipped a switch. After pitching seven innings of three-run ball on Thursday, Godley’s season ERA sits at 2.53. He added eight strikeouts to just one walk for an FIP of 3.17. And his home run-per-fly ball rate isn’t that low, either, as he has an xFIP of 3.23. Godley has made just nine starts this year, but he’s already been the third-most valuable starter in Arizona with his most recent outing bringing him up to 1.5 fWAR for the year.
Godley is dominating with the Keuchel weapon: the ground ball. His 59.9 percent ground ball rate is 15.5 percentage points above the league-average, and it ranks sixth among Major League starters with at least 50 innings pitched. While his ground ball rate still lags behind that of Keuchel — the ground ball king — by a wide margin, Godley’s ground ball performance has reached elite levels.
Check out his spray heat map, with darker colors meaning more batted balls in that area:
Now, let’s compare that to Keuchel’s:
Both pitchers live with the ground ball. Keuchel’s are more centered around third base, while Godley’s are more evenly dispersed around the left and center side of the infield. Let’s compare these heat maps, now, to Ervin Santana’s heat map, to get a real idea of just how many ground balls they are generating. Santana has a 44.4 percent ground ball rate this season, exactly MLB average.
You may be thinking, “What’s the difference here?” While it does look like Santana’s batted balls are concentrated around second base, which would make them grounders, you need to take a look at the bigger picture. Check out how much yellow there is in the outfield on Santana’s chart. Now compare that to the amount of yellow on Keuchel’s or Godley’s charts. Both have parts of their outfield that are uncolored; Santana cannot say that. So, while many of his batted balls in the infield may be concentrated around second base, Santana allows lots of fly balls all around the outfield as well; that’s why there’s not a dark color there.
That’s not all, though. Godley’s infield fly ball percentage has jumped from 6.0 percent last year to 12.9 percent this year. He’s also getting more strikeouts, too, as his strikeout-minus-walk rate of 15.9 percent has leapt above the MLB-average threshold. To add to this newfound dominance, Godley’s average exit velocity against — minimum 100 batted ball events — is tied for the fourth-lowest in the majors, at 83.6 mph. Coincidentally enough, that mark is tied with — you, guessed it — Dallas Keuchel (and Rich Hill, too).
What makes this Keuchel comparison even more interesting is the fact that both are late bloomers. If this is truly is Godley’s breakout season, then he’s having it at age-27. Keuchel was a below-average MLB pitcher until posting a 2.93 ERA in 2014, his age-26 season. Then, at 27, Keuchel won the AL Cy Young.
Regardless, at Beyond The Box Score, we’re not here to tell you that someone is better. We are here to provide our best analysis as to why someone is better. It’s not hard to see that Zack Godley has changed, but I’m going to try and figure out why he has developed into a solid pitcher.
A quick look at Godley’s preview on BrooksBaseball.net might give us the answer:
His curve is thrown extremely hard, generates a high number of swings & misses compared to other pitchers' curves, has primarily 12-6 movement and results in many more groundballs compared to other pitchers' curves.
His curveball could be the explanation for why Godley is improving in so many categories across the board. His ground balls are up, and according to this, Godley’s curve generates “many more” ground balls when compared to other pitchers’ curves. Plus, the high number of swings-and-misses potentially explains the increase in strikeouts this season.
According to PITCHf/x data, Godley has used his curveball more this season than ever before. Currently, 31.7 percent of Godley’s pitches have been registered as curveballs, a steady increase from his 11.8 percent mark in 2015 and his 25.3 percent mark in 2016. His curveball has been 10.5 runs above average, according to pitch linear weights, making it the second-best curve in the Major Leagues, behind only Corey Kluber. Hitters are hitting just .119 with a .136 slugging percentage against it.
Godley’s curveball — and its increased usage — have made the worlds of difference for him this year, but it is not the only reason why he generates so many ground balls. Neglecting to mention his sinker would be doing Godley a disservice. Almost 14 percent of all his sinkers are put on the ground, and since he has thrown that more than his curveball, it cannot go unnoticed.
In order to generate ground balls, Keuchel does not rely nearly as much on secondary stuff as Godley does. In fact, 54.2 percent of Keuchel’s pitches are four-seam fastballs, ranking just 0.5 percentage points below the league average. Godley throws his fastball less than 40 percent of the time.
While they might achieve their success by using different pitches, both Godley and Keuchel know that throwing a pitch in the bottom part of the strike zone is the key to ground ball success. Let’s take a look at their zone profiles.
Godley has thrown 716 pitches tracked by MLB’s Statcast. Per this chart, 308 of them (about 43 percent) have come below the strike zone. Another 120 (about 17 percent) are in the bottom third of the strike zone. It’s evident that Godley knows he needs to keep the ball down to goad opponents into hitting it down.
Now, here’s Keuchel’s:
Keuchel has thrown 1,038 pitches that have been tracked by the Statcast system this season. This breakdown shows us that 545 of them have come below the strike zone (about 53 percent). Another 269 (about 26 percent) are in the bottom third of the zone.
What can we draw from this? Godley is trying to emulate what Keuchel does, and he has had great success. There is only one Dallas Keuchel, and Zack Godley isn’t quite as good. But, if Godley can be even 75 percent of the pitcher that Keuchel has been over the last few years, the Diamondbacks may have found themselves a very useful hurler as they look to contend in 2017 and beyond.
All stats current through games played on June 22, 2017.
Devan Fink is a Featured Writer for Beyond The Box Score. You can follow him on Twitter @DevanFink.