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Carson Kelly Is Quietly Having A Breakout

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Another part of the Goldschmidt trade, Carson Kelly is quietly off to a great start this season.

Arizona Diamondbacks Photo Day Photo by Christian Petersen/Getty Images

The position of catcher is a hot topic among Dbacks fans. Despite the controversy of regularly carrying three catchers, the Diamondbacks are getting great defense from the catchers (all three rank among the best in called-strike rates in the MLB) and good results from the pitching.

We all know about JRM’s struggles to make contact. Alex Avila has been known for being a great defender and his bat has rebounded back to form after a down year in 2018. But today’s story is about Carson Kelly, one of the two main pieces of the Paul Goldschmidt trade, who has very high expectations and has been a highly-regarding catching prospect for many years in St. Louis. And due to a lack of playing time, he has largely remained an unknown to the baseball world.

That is slowly starting to change. We’re almost through May and Carson Kelly has received 89 PA, which accounts for almost 43% of our PAs from catchers this season. And while it’s still early, we can learn a few things about Carson Kelly already. And there is a lot to like.


The Defense

This is the easiest and most obvious thing to talk about but it needs to be highlighted none-the-less. The first thing that stands out with Carson Kelly is that he is an excellent pitch framer. Per Statcast, Kelly ranks 7th in called strike rate among MLB catchers, which is incredibly amazing considering the Diamondbacks have the single lowest rate of pitches thrown in the strike zone in the MLB. Kelly is counted as one of 22 catchers that have added “extra runs” via strikes per Statcast.

But it’s not just pitch framing with Kelly. Admittedly it’s a small sample, but Kelly has a 1.99 pop time for steals at second base (only 4 attempted on Kelly), which is slightly better than average for catchers. Furthermore, Kelly has 2 DRS in only 188 innings. And while there are several catches with 2 more DRS, they almost all have more innings caught than Kelly.

Carson Kelly isn’t yet an elite defender at catcher, but he’s trending in the right direction. He excels in all parts of the game defensively. It’s very possible that he can continue to improve as he gets more experience behind the dish in the MLB.


The Offense

This is most obviously the main focus of this article as it was to be expected that Kelly would be a good defensive catcher. And as expected, this is where Carson Kelly is having his breakout.

Keep in mind, we’re only looking at 89 PA so this is going to be kept at a high level. The focus will be on what skills Kelly is showing so far and will be monitored as the season goes on.

Plate Discipline

The first thing that stands out for Carson Kelly is that he is showing some pretty impressive plate discipline, especially for a 24-year-old that has spent the past three years riding the bench behind Yadier Molina. One might expect him to be aggressive when given his chance. However, the opposite has been true:

K%: 18.0%

xK%: 17.9%

BB%: 10.1%

Unfortunately, there is no reliable xBB% for hitters (yet) but these are promising numbers to see from such a younger hitter. We’ll obviously want more time to see how Kelly sustains this but so far, it appears that Kelly has a good eye at the plate. His 27.2% O-Swing% (swings at pitches outside the zone) is among the lowest third of all MLB hitters. His 79.9% contact% is among the top third of MLB hitters. Interesting enough, he is second on the team in pitches per plate appearance, behind only Alex Avila, who is sitting on a mind-boggling 32.4% BB%. While that won’t last, Avila does have a career 14.4% walk rate. That seems like it might just be within Carson Kelly’s reach.

Another thing to look at is how Kelly is getting pitched. As mentioned previously, one of the easiest ways to tell if a batter is improving is that their Zone% or number of pitches that pitchers throw in the strike zone drops. This might be the case for Carson Kelly:

Again, this is early but these are all positive signs for Carson Kelly.

The Power

This is the other part of Kelly’s offensive profile and it is very important. In addition to improved plate discipline, Kelly is also making improved contact at the plate. First of all, he’s hitting the ball harder:

As a result, his expected slugging percentage (xSLG) has increased by over 50 points:

Putting it all together and Carson Kelly has upped his xwOBA this season to .311. That is a bit lower than his current .353 wOBA, suggesting that Kelly has been a bit lucky this season, but a .311 wOBA would put him just a tad below league average... in the roughly 90-95 wRC+. This isn’t great, but again we’re seeing a 24-year old make his first real meaningful development at the MLB level. It’s nice to see him succeeding so far.

Kelly’s biggest problem isn’t actually in how hard he’s making contact - he does it at a decent rate and at a decent power level - the problem is that he hasn’t quite figured out how to square up MLB pitching yet. He only has 2 barrels on the season, rating pretty poorly (259th) in barrels/PA.


Carson Kelly isn’t storming baseball with his bat, but he’s showing promise. He has good overall discipline and is now starting to combine it with some decent power potential. He’s probably a league average (100 wRC+) at best right now, but he has plenty of room to grow. Defensively, he’s already shining and again has lots of room and time to grow into a great defender.

This isn’t a breakout in the traditional sense, but considering that Kelly has taken a backseat to Yadier Molina for the past three years, it’s a breakout to see Kelly playing at a league average level. Which, for a 24-year-old catcher, is actually rather impressive.

Between Luke Weaver looking more and more like a future ace with each passing start and Carson Kelly looking like a league average catcher with plenty of upside still the come, the Diamondbacks are striking some huge early gold with the Goldy trade. The Diamondbacks still have 9 more years of control for Weaver and Kelly. It’s quite possible that they will be come a staple in the lineup for years to come.