Zach Davies Analysis follow up Using R: 2020 Season

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Note: This is a direct follow up analysis to his 2019 breakdown, which can be found here:

To simplify, here are the takeaways taken directly from the previous analysis:

“Things that can help Davies avoid a possible regression is to increase the usage of his changeup. It’s by far his most effective pitch in terms of producing whiffs and outs, with above average movement. Incorporating this even more can eventually translate into even more swings and misses, unlike his slider (which he ultimately stopped throwing half way through the year), and his curveball, which he may want to think about using even more sparingly than he already does, despite its above average spin rate. Davies may want to think about developing a new pitch, however, that is much easier said than done. Another aspect is to limit the amount of cutters he uses, especially to lefties, and avoid those dreaded hitters counts. He can go back to his roots as a true sinker baller and keep the ball on the ground more by increasing the usage of it, particularly against lefties. He can also be a bit predictable on certain counts, so mixing up his pitches is key.”

2020 Season

Zach Davies took a leap in his 2020 season numbers wise, and his career continues to be trending in an upwards direction. After analyzing his 2019 season, it appears he built upon his strengths, although something to note is this analysis is based on a shortened 60 game season sample size.

Pitch Usage

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Comparing pitch usage to R and L in 2019 vs 2020

In the previous analysis, it was pointed out that Davies greatly needed to increase the usage of his changeup, as it was by far his most effective pitch, producing a xwOBA of .312, a whiff rate of 29%, and a putaway rate of 16.7%, all highs of all his pitches in 2019. It appears he did just that. He increased his usage of that pitch by exactly 10% in 2020, throwing it 41.3%. Increasing the changeup usage meant others in his arsenal were affected, and it happened to effect his primary pitch, the sinker, the greatest. He decreased his sinker usage a little more than 10%, evening out his usage between the sinker and changeup. He is essentially a two-pitch pitcher to righties, and has a 3 pitch arsenal to lefties.

Based on the splits, Davies appeared to stick to his tendencies in both years, favoring righties with his sinker and changeup, while favoring lefties with the cutter. It was also mentioned that he could be wise to even further lessen his usage of his curveball and slider, and in 2020, he dropped his curveball about 1%, and completely got rid of the slider in 2020, by far his least effective pitches.

Pitch Location

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Pitch location comparison between 2019 & 2020

In 2020, it appears Davies migrated from the corners more towards the middle of the plate, but much lower in the zone. This is most likely due to his increased changeup usage and better sinker placement. He mainly hits the very bottom of the zone, but does however hit the middle part of the zone more often. Davies saw his groundball rate increase from 41.5% to 43.3%, and conversely saw has flyball rate fall about 2% as well, most likely as a result of keeping the ball down more often, even with decreased sinker usage.

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On the left is every changeup Davies threw in 2020, and on the right is every changeup that was swung at and missed. He keeps it low in the zone for the most part, and was clearly getting swings and misses on changeups well below the zone, even some in the dirt. He saw his changeup’s whiff% increase from 29% to 35.9%, and its putaway% rise from 16.7% to 27.2%. It also lead his pitches in xBA, xSLG, xwOBA, and avg exit velocity, by a decent margin. His sinker and cutter remained relatively the same. He elected to use his best pitch much more in 2020 as suggested, and it paid off becoming even more effective. Again, this is based off a 60 game sample size.

Situational Pitching

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% of pitches thrown in each count

Davies looked to be a little less predictable in 2020 than 2019, and most of it has to do with the increased changeup usage. His confidence in it to produce a strike is astounding, as it was his most used pitch on 1–0, 1–1, 2–1, and 3–2 counts, all crucial counts where a strike is needed. In 2019, Davies’ preferred putaway pitch was the sinker, and that changed dramatically as he threw it 62% of the time in an 0–2 count vs righties. In fact, it’s his most used pitch on any two strike count. He does not throw the change on 3–0, but seems to like it on 3–1 and 3–2, and when factoring in his two strike counts, it’s interesting to find that his strikeout % rose to a career high 22.8%, up from 15.2% in ’19, and his walk rate lowered about 1% as well.

Stats Deep Dive

Zach Davies saw just about every stat improve in his shortened 60 game 2020 season, and there can be a direct correlation with his increased use of his changeup, with its stats mentioned earlier. Overall, Davies saw his ERA, xERA, FIP, xFIP, and his xSIERA, all decrease pretty significantly. Although his below the surface numbers were the ones screaming regression, it appears he managed to avoid it.

His pull % increased 4.7% from last season, which correlates with his increased groundball %, and is great for a sinker-baller, and his hard hit % also decreased almost 10%.

What’s most interesting is the fact that Davies threw pitches in the zone at a higher percentage than in ’19, yet his zone contact% decreased 6%, and his chase% stayed about the same, yet his chase contact% decreased a whopping 13.1%, down to 59.7%, a career best. Hitters were making much less contact with pitches out of the zone than they did a season ago, most likely attributing to his changeup that achieved a career high whiff% as well.

He still outperformed most of his expected stats, so a full 162 game season would have shown whether this 60 game stretch was sustainable, and he did struggle in two postseason starts. These include, BAA, ERA, wOBA, and a low BABIP of .249, along with a career high left on base percentage of 78.2%. Another thing to note, was that Davies only faced teams in the West this season, which makes it even more impressive that hitters seeing him over and over again were still struggling.


The 2019 analysis of Zach Davies showed that he was due for regression, and that in order to avoid this, he needed to make a change, the main aspect being using his most effective pitch, the changeup, much more. He did just that increasing the usage by 10%, and used it in crucial count situations. It is no surprise that he saw career highs in every swing and miss and contact categories, which in turn will reflect in his expected stats, and his surface stats. Another recommended change was to lessen the usage of his curveball and slider, and he lowered the use of his curveball by about 1% and didn’t throw one slider in 2020.

He also did a better job of mixing up his pitches as he could become predictable in some cases, as mentioned in the last analysis, and he adjusted by not using the sinker as much in obvious fastball counts, and replaced it with that nice changeup, which he appears to have full confidence in.


“Baseballr” & “Lahman” packages in R/RStudio

Other Projects

Github Code For This Analysis

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