What’s Going on With Joey Bart’s Power?

When Buster Posey announced his shock retirement at the close of the 2021 season, fans were dismayed—but also tentatively hopeful. It seemed that, despite protestations to the contrary, the San Francisco Giants’ front office had seen this coming; they had taken two catchers with their top picks in two of the last three drafts (Joey Bart at #2 overall in 2018 and Patrick Bailey at #13 overall in 2020).

Of the two, Bart was the more lauded pick. A Georgia Tech product, he won the ACC Baseball Player of the Year in 2018 and the Buster Posey (Johnny Bench) award—given to college baseball’s top catcher. Scouts raved about his in-game mentality, his ability to call games, his defense behind the plate, and his immense raw power. There were concerns about the hit tool and the high K rate, but the belief was that as long as Bart could hit just enough to stick in MLB, his raw power would make up the difference.

As Giants fans have seen this season with Blake Sabol, towering home runs can make up for limited plate discipline (Sabol has a wRC+ of 104 despite striking out 34.7% of the time). The point of this is, with Bart, the outstanding question was always whether he would hit enough to get to his power, not whether his power would be there.

And yet, in 158 MLB games and 492 plate appearances, Bart has hit just 11 home runs. To give you a sense of how limited this is, let’s look at AB/HR — the number of at bats per home run hit. The lower this ratio, the more frequently a player hits a home run. Aaron Judge has the best AB/HR ratio in modern-day baseball, at 11.7 AB/HR.

Buster Posey, never known for his power, had a career AB/HR of 31.4. Bart currently stands at 40.7. In 2023, yet to hit a home run, Bart is at DIV/0. He is slugging .295, so it’s not that he is hitting a bunch of doubles and triples to go along with no home runs; he just hasn’t shown any flash of the power we know he possesses. His overall wRC+ is 64, a function of the lack of slugging and a concerning 2.4% walk rate, leading to a .286 OBP.

But Bart is also striking out the least in his career at a 25% K-rate. In 2022, this K rate was 38.5%. Usually, when players improve their K-rate by that much (-13.5%), it means they are being more selective about the pitches they are swinging at and improving their overall plate discipline. This should, in turn, lead to better outcomes; driving pitches to hit means higher quality of contact.

But that’s not the case with Bart. My theory is this: Bart has sacrificed his power for contact, and as a result is making weak contact on pitches both in and out of the zone, rather than being selective about what pitches to swing at, which is leading to lower exit velocities and worse outcomes.

Let’s investigate this theory. If it is accurate, a few things will be true:

1. Bart’s swing rate will not have changed much
2. Bart will be making contact on more pitches
3. His quality of contact will be down

Note: all data from Fangraphs, and most comparisons will be 2022 vs. 2023.

Swinging at pitches

Fangraphs provides us with a useful statistical set, known as Swing%, which they also divide into O-Swing% and Z-Swing%. O-Swing% refers to the percent of pitches swung at outside the zone, and Z-Swing refers to the percent of pitches swung at within the zone. Swing% is the overall percentage of pitches swung at.

In 2022, Bart had an O-Swing of 33.5% and Z-Swing of 64.7%, leading to an overall swing percent of 46.9%. In 2023, Bart has an O-Swing of 33.9% and Z-Swing of 66.7%, leading to an overall swing percent of 48.3%.

This represents a slight swing% increase, coming primarily from swinging at more pitches within the zone, but by itself is not any cause for concern. Elite hitters generally will have a much lower O-Swing%, as you want to swing (hypothetically) at very few pitches outside of the zone, but given Bart’s calling card was never his plate discipline, this represents a longer-term issue and not a change between years. League average O-Swing% for 2023 is 31.5%.

It does, however, point to the fact that the mix of pitches he is swinging at remains subpar.

Contact rate

Fangraphs also provides a statistical set: O-Contact%, Z-Contact%, and Contact%. Each of these represent the amount of times a batter makes contact on a pitch they have swung at. Again, O-Contact refers to this contact % on pitches outside of the zone, and Z-Contact refers to this % inside of the zone, while Contact is the overall percentage.

In 2022, Bart had an O-Contact of 42.4%, Z-Contact of 73.8%, and Contact of 64.0%. In 2023, Bart has an O-Contact of 51.9%, a Z-Contact of 84.4%, and a Contact of 73.2%—an overall increase of 14% or 9.2 p.p.. This is an enormous change. No other Giant (minimum 100 PA) has an increase in Contact% of more than 1 p.p. between those two years. Bart’s 64.0% contact rate ranked him dead-last for the 2022 Giants, and his new contact rate is ranked 6th overall (min. 50 PA) for the 2023 Giants.

So the first leg of the hypothesis is complete: Bart is definitely swinging more. But this isn’t a bad thing in a vacuum—his contact rate was very low before, so isn’t it a good thing he’s making more contact?

Quality of contact

Contact doesn’t exist in a vacuum. While most of us probably couldn’t make contact with an MLB pitch, hitters that can have to be discerning about which pitches they do make contact with because soft or weak contact leads to easy outs for defenders. You’ve seen it a hundred times on TV, a guy taps the ball weakly to short or pops up to shallow center. Those are the kind of at bats you generally do not walk back to the dugout feeling good about.

There are a few ways to measure the quality of contact, but I’m going to let Fangraphs do the work for me. They report a stat known as Soft%, Med%, and Hard%. The calculations are proprietary, but the rough conclusion is between exit velocity, hang time, and trajectory, you can rate how well a ball was struck. And the more balls that are hard-hit, the better your quality of contact. For context in 2023, the league average across these stats is: Soft% = 14.7%, Med% = 53.3%, Hard% = 32.0%.

In 2022, Bart’s stats were: Soft% = 23.5%, Med% = 43.0%, Hard% = 33.6%. In 2023, to date, they are: Soft% = 17.5%, Med% = 59.6%, Hard% = 22.8%. Essentially, he has lost 11.4 p.p. off his hard hit contact — he has seen a 33% decrease in the percentage of balls he hits hard. He has also decreased his soft contact%, but that has led to an enormous increase in his med%. Basically, when Bart makes contact, nearly 60% of the time he is going to make medium contact on the ball. While this can be better than soft contact, it is not the kind of contact that goes for home runs and extra base hits with frequency.

While medium contact may not sound so disastrous on its own, a 2015 Fangraphs article explains that both medium and soft contact is correlated with lower batting averages, slugging, lower wRC+, and all the other stats that represent worse outcomes for a hitter.

In conclusion...

To summarize, Bart has started making significantly more contact (a +14% increase from 2023) on pitches, but has been making much weaker contact (a -33% decrease in the number of hard-hit balls since 2023). These two facts together tell the story that while he is being more aggressive at the plate in terms of swinging at strikes, he is also making worse contact as a result and it has sapped his power.

Bart still possesses raw power, but that might not matter much if he can’t get to it because his contact is too weak. Perhaps the Giants charged him with lowering his K-rate, which he has successfully done. But not striking out doesn’t mean much if the balls you put in play don’t go anywhere.

As Bart returns from the IL, keep an eye on his Soft%, Med%, and Hard%; when the latter begins to tick up, you’ll know Bart is starting to perform to his true potential.