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2018 Arizona Diamondbacks Reviews # 15, Zack Godley

The bull has a mighty curve!

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A remarkable season for the bull.
A remarkable season for the bull.
Photo by Pablo Blazquez Dominguez/Getty Images

2018 rating: 5.77

2017 rating: 8.08

2018 salary: league minimum

2018 performance: 15-11, 4.74 ERA (FIP 3.82), 178.1 IP, 177 H, 103 R, 94 ER, 16 HR, 81 BB, 185 SO

2019 status: He is on the D-backs 40-man roster, and he is projected to be on the 25-man roster in the pitching rotation. His nickname is the bull.

His curve is among the best pitches in the Majors

Let’s look at the 2017 season. In a Fanpost for the AZ Snakepit, travenson wrote that as measured by FanGraphs’ pitch effectiveness (wCH/C), Zack Godley’s curve (2.40) was the the seventh most effective pitch in the Majors. Interestingly for the D-backs, Zack Greinke’s changeup (3.48) was the fifth most effective pitch.

Let’s look at April and May of the 2018 season. Eno Sarris wrote that as measured by a weighted average of whiff-rate and groundball-rate, Zack Godley’s curve (16.1% whiff rate, and 53% groundball rate) ranked 14th in the Majors. Based on velocity and movement, Zack Godley’s curve (82.4 mph and 3.4 zmove) ranked 10th in the Majors. Interestingly, Eno Sarris wrote that fastball command and pitch deception make a difference in curve effectiveness.

In summary, Zack Godley’s curve is awesome!

Signs he played well this season.

Three insightful statistics:

  • His strikeouts (185) and strikeouts-per-9-innings (9.3) ranked 9th in the NL.
  • In the last two seasons, when he throws strikes, his 52% percent of balls in play is better than his previous two seasons (56% and 57%).
  • His 18 putouts tied as the fourth best pitcher in the NL.

Signs he played worse this season.

Three insightful statistics:

  • His hits-per-9-innings (8.9) was higher than last season (7.2).
  • His walks (81) ranked a tie for 3rd highest in the NL.
  • He led the NL in wild pitches (17) and tied for first in hit batters (12).

This season had four phases.

The following graph shows the story. The four statistics are earned runs average (ERA), strikeout rate per batter faced (K/BF), swinging strike percent (SwStr), and home-runs per 9 innings (HR/9).

Data Source: Baseball Reference

The start of the season was not good. His velocity declined, his command worsened, and his strike percent was declining.

He successfully tweaked his delivery to achieve excellent results in phases 2 and 3. Most especially, phase 3 shows his potential in 2019.

In case you want to look deeper, the following chart shows data..

2018 Season

Zack Godley 4/3- 6/9 6/10-7/23 7/24-8/17 8/18-9/29
Zack Godley 4/3- 6/9 6/10-7/23 7/24-8/17 8/18-9/29
starts 12   8 4 8
ERA   5.12   3.97   2.36 6.53
K % 21.00 25.60 27.36 22.46
SwStr 10.50 13.80 12.28 10.93
BABIP 0.316 0.314 0.286 0.377
HR/9   1.38   0.40   0.00 0.87
Data Source: Baseball Reference

At the end of the season, something changed for the worse. Two possible explanations follow.

Strike one! Locating his curve and backing it up with a good fastball is important. “It’s been about fastball command and the ability to get strike one.” – Torey Lovullo, August 2018. Let’s look at the first pitch of an at-bat. This season for Zack Godley, comparing batter-hits to batter-outs at several pitch counts shows (Data source: Baseball Reference):

  • At the first pitch of an at-bat, hits-to-outs is 0.32.
  • A first pitch ball increased hits-to-outs from 0.32 to 0.43 (Batter advantage).
  • A first pitch strike left hits-to-outs about the same (.35 vs .32).
  • If the count reaches 0-2, hits to outs dropped to 0.11 (huge pitcher advantage).

Although this may seem like common sense, this season’s data show that it really was about getting strike one. Whether this caused the crash is an unanswered question.

His pitch mix. Does his sinker to righties stink? Is his cutter to lefties is too cute? Let’s look at adjusted slugging XSLG and XwOBA from Statcast:

Right-handed batters:

  • Curve .315, .251
  • Sinker .578, .395
  • Cutter .377, .362

Left-handed batters:

  • Curve: .285, .257
  • Sinker: .335, .348
  • Cutter: .487, .446
  • Change: .265, .338

I have bolded the two lines that show batters are doing better against the sinker for righties, and the cutter for lefties. Whether this caused the crash is an unanswered question.

This season revealed a weakness in throwing to the bases.

To add context, let’s look at his fielding performance. In the last three seasons, his fielding percent was consistently below league average for pitchers (.919 vs .952 in 2018). Just like last season, he had three errors; this season they were all in July and August. In summary, he is not going to win a gold glove, and that would be an unreasonable expectation.

Let’s look at keeping base-runners from advancing. For the season, his 42% caught stealing was better than league average (28%). The importance of pick-off throws is overrated. Dan Malkiel wrote that he “found no evidence that throwing to first is an effective means of curtailing base stealing.”

On 21 July against the Rockies, people noticed he had difficulties throwing to the bases. The first 3 innings were clean. In the next three innings Godley had problems: 1 throwing error, 2 wild pitches, 4 walks, 1 stolen base, 2 singles, and 3 extra-base hits. Perhaps avoiding wild pitches and walks would have had a greater impact than better throwing to the bases. In the last two seasons, he led the National League in wild pitches (13 and 17 wild pitches). This season, he tied Urena and Scherzer in hit batters.

“There’s a lot of things that we can do to help.” — Torey Lovullo. And that’s what happened. In the last 28 days of the season, his 33% caught stealing was better than league average, he improved to 1 wild pitch, he hit no batters, and he earned 2 assists.

The problem throwing to the bases was overblown out of proportion.

The bull has a mighty curve.

This season has been a great developmental experience for Zack Godley. He improved his awesome curve, and he adjusted to batters in the Majors. By the end of the season, he reduced wild pitches and hit batters. He is developing into one of the best pitchers in the Majors.