In Carson Kelly, Diamondbacks might have their long-term catcher

Unlike Goldschmidt, Kelly has thrived in his new environment. Serving as the Diamondbacks’ primary catcher, Kelly has slashed .275/.352/.538 (123 wRC+) with 10 home runs in 193 plate appearances. Most of the right-handed Kelly’s damage at the plate has come against lefty pitchers, whom he has destroyed for a line of .383/.473/.766 over a small sample of 55 PA, although he has also been playable against righties. Thanks in part to his impressive offensive output, Kelly has already totaled 1.7 fWAR, which ties for seventh among catchers and happens to easily outdo the minus-0.2 Molina has mustered to this point. It even upstages Goldschmidt’s 0.7.

Adding to his value, Kelly has been an outstanding defender in his first year in the desert. That isn’t necessarily a surprise, as Kelly was a lauded backstop during his days as a prospect. Nevertheless, the fact that he’s delivering in that area in his first extensive action in the majors is no doubt comforting to the Diamondbacks.

According to Baseball Prospectus’ Fielding Runs Above Average metric, only 15 catchers have been superior defenders to Kelly this season. He’s the game’s sixth-best blocker and its 24th-ranked pitch framer, per BP, and has also held his own at the less obscure art of throwing out runners. Kelly has caught nine of 25 would-be base stealers, giving him a 36% success rate which ranks 9% better than the league-average mark.

While Kelly does indeed look like a legitimate starting catcher, the question is whether he’s this good. On the offensive side, probably not, says Statcast, which indicates there has been substantial luck behind his .368 weighted on-base average. Kelly’s wOBA places him in company with All-Star Gary Sanchez, yet his .311 expected wOBA aligns him with Tyler Flowers and puts him in the majors’ 30th percentile. Kelly’s also below average in terms of expected batting average (16th percentile), expected slugging percentage (42nd), hard-hit rate (48th) and exit velocity (48th). That said, hanging around the majors’ 50th percentile as a hitter isn’t the worst outcome for a catcher, especially when you’re as adept as Kelly is behind the plate. Backing up BP’s framing numbers, Statcast places Kelly in the league’s 96th percentile in that area.

Although Kelly’s production as a hitter this year might not be sustainable, you don’t need to be a force at the plate to serve as a quality starting catcher. Just 18 backstops, Kelly included, have cleared the 1.0-fWAR bar this season. Furthermore, even if Kelly’s offense wanes, his defensive chops give him a high floor, which could help make him the Diamondbacks’ answer at his position for the foreseeable future. Kelly won’t be eligible for arbitration until after 2020 or free agency until the conclusion of the 2024 campaign, so Arizona might not have to look for another primary catcher for a while.