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Zach Davies

His pitching performance will likely be impressive.

Zach Davies.
Zach Davies.

Last season, the Diamondbacks had 16 pitchers start at least one game. This season, the Diamondbacks need starting pitchers so they have better depth.

On 24 March, they signed another starting pitcher, Zach Davies. His base salary is $1.5 Million with incentive pay of up to $2.5 Million based on how many games he starts.

Four Diamondbacks pitchers, including Zach Davies, have Boris Corp. as their agent. The others are Ian Kennedy, Luke Weaver, and Zac Gallen. These players are talented.

His career best seasons were 2019 and 2020.

When he started the 2019 season, he was on the mend from rotator cup inflammation and lower back tightness, so he did not work on all his pitches in spring training. In 2019, he increased how often he pitched his changeup (from 12.3% to 31.3% of his pitches). Perhaps surprisingly, his changeup’s .239 wOBA was his best pitch.

In 2019, his 125 ERA+ was a career best. He was an above average starting pitcher.

In the offseason, the Brewers traded him to the Padres. In the 2020 season, he further increased how often he pitched his changeup (from 31.3% to 41.3%).

In addition, he increased how often he pitched his cutter fastball (from 11.8% to 14%). His changeup’s .229 wOBA was his best pitch for a second consecutive season. His cutter’s .300 wOBA was an improvement from .343 wOBA the previous season.

In 2020, his 154 ERA+ was a higher career best. Again, he was an above average starting pitcher.

“His changeup was this really really amazing pitch at times.” — Paul Sporer, July 2021

His approach is organized.

About a year ago Zach Davies talked about spring training. What I heard was that his season preparation process has four top-level steps:

  • Tune up his mechanics.
  • Fine tune his timing.
  • Focus of command & pitch location.
  • Work on pitch selection

In that context, he said that communication is an overarching priority. “Communications is the biggest thing [in spring training], especially coming to a new organization and meeting new players.” — Zach Davies

He is consciously avoiding the dead-end destination of being a starting pitcher with only two pitches. “It’s really just going into games with the desire to throw different pitches. It’s forcing myself to throw curveballs and cutters, everything in every count.” — Zach Davies

He has a [game specific] goal in the first couple innings of a game. After those two innings, he sometimes makes an adjustment. “That [adjustment] changes team to team – I try to adjust as fast as I can.” — Zach Davies

What happened in his 2021 season?

In the offseason, the Padres traded him to the Cubs. Pitching for the Cubs, his 2021 results were no longer excellent. Examples follow:

  • His ERA+ fell from 125/154 to 74.
  • His 4.56 walks per 9 innings was a career high.
  • His 1.52 homers per 9 innings was a career high.
  • Although not a career low, his 22.8 K% fell to 17.1 K% (22% is excellent, 20% is about average, and 18% is poor).

If he had been a free agent after his 2020 season he would have commanded a salary of $14 Million per year (based on his 1.75 WAR average of bWAR and fWAR for two seasons, and based on $8 Million per WAR). That salary would have been unaffordable for the Diamondbacks.

His stumble in the 2021 season made it affordable for the Diamondbacks to acquire him for the 2022 season. Signing him was great because he has potential to be an above average starting pitcher. My optimistic view is that many pitchers, especially those who are young (Zach Davies is a 29 years young), make adjustments and bounce back from a down season.

Often overlooked are great things that happen during challenging times. During that darker season he had a shining game against the Dodgers. He pitched six no-hit innings. The relievers (Ryan Tepero, Andrew Chafin, and Craig Kimbrel) added 3 no-hit innings. It was a combined no-hitter!

What do the detailed statistics tell us?

To find insights on what went off-course last season and what could be set-right this season, let’s look at his four main pitches. The following table shows frequency of his pitches and their results from 2018 to 2021.

Zach Davies, selected pitches. Data from Baseball Savant.

Last season, cutter frequency dropped, possibly because an increase in homers per pitch. Possibly related, sinker frequency increased. My view is that this change in pitch mix may have been an overreaction because his cutter had a better wOBA than his sinker, despite the increase in homers per pitch.

Last season the curve had great results. My view is that its use could be increased from 7.1% of pitches to perhaps 15% of pitches.

I noted that Paul Sporer and Nick Pollack said one problem that Zach Davies had was a low rate of batters swinging at fastballs outside the strike zone. My view is that whether batters swing at pitches outside the strike zone is not critically important to Zach Davies for two reasons:

  • He is more of a pitch-to-contact pitcher than a strikeout pitcher.
  • His ground ball percentage was higher than his fly ball percentage every season in the Majors.

My eureka moment was when I realized that two strike counts were most important when Zach Davies said he wanted to pitch everything in every count.

For his four most frequent pitch types, the following table shows wOBA for 2-strike counts and non-2-strike-counts, and for pitches in the strike zone and outside the strike zone.

wOBA for Zach Davies, selected pitches, 2021 season. Gameday zone determined whether pitch was in the strike zone. Data from Baseball Savant.

Last season, nearly all his pitches had better results in 2-strike counts, whether or not the pitch was in the strike zone. Two exceptions were his cutter outside the strike zone and his curve inside the strike zone because they had better results before the 2-strike count was reached.

Based on the table, two conclusions are possible.

  • His results could be improved by subtly changing the pitch mix, taking advantage of Zach Davies’ excellent pitch control in locating pitches.
  • His sinker should not be pitched outside the strike zone.

This season his spring training is building momentum.

He has not yet pitched in spring training. It’s been less than a week since he was signed, so he had not yet completed his very organized four step spring training process. Because he likely made (or will make) adjustments from last season, his spring training process will likely be longer than normal. That’s when he will be ready - at that point he will likely be an above average starting pitcher. In the following quote, although ‘ready to go’ could have meant stretched out to pitch more innings as a starter, optimistically it also meant ready to pitch as an above average starting pitcher.

“Based on my conversation with him he is in a good spot. He feels like he is starting to ramp up. So I feel yes there is a possibility he is going to be ready to go a lot sooner than later.” — Torey Lovullo, 25 March, 2022.


In 2019 and 2020, Zach Davies was an above average starting pitcher with career best performances. He stumbled in 2021 as he reached free agency. The Diamondbacks signed him for an affordable salary, especially if he bounces back to his recent performance levels.

Statistics suggest possible ways to improve his pitching performance. It’s likely he made adjustments in the offseason and spring training. When he has fully integrated those adjustments into his process, it’s likely his pitching performance will be impressive.