Relative down year expected for Merrill Kelly in 2024

Kelly's projection is a bit disappointing at first glance. From a raw data perspective, these systems are projecting his worst statistical season since 2021 (a year in which the D-backs were 52-110). Both systems expect an ERA close to 4.00, with Steamer expecting nearly a full run higher than 2023. Both systems expect a notable drop in strikeout % and an increase in home runs per nine. 

They do, however, see Kelly returning back to his previous standard of walks. Kelly saw a surprising rise in walks in 2023, and both ZiPS and Steamer expect him to decrease that by a good margin. They both project a slightly higher FIP than ERA.

With a semi-large disparity between Kelly's stats in the nightmare season and his recent years of solid pitching, it makes sense that these projection models would calculate a return to the mean. However, none of his projected metrics rank far below average. Even with regression all around his projected stat line, Kelly still looks respectable ahead of 2024.

Why Kelly might outperform this projection

D-backs fans have seen what Kelly can do. A crafty veteran with excellent control, an ability to catch guys looking and a brilliant changeup, Kelly ranks in the 96th percentile in total pitching run value (22). His offspeed pitching value was second to none, with his changeup having by far the best individual run value (16) of his six pitch arsenal, five ahead of his four-seam fastball (11).

Kelly ranks in the 88th percentile in getting batters to chase outside the zone. But his versatility is the most impressive aspect of his game. Kelly ranked well above average in strikeout %. However, despite being able to punch batters out at a good rate, his ground ball rate sits at a solid 45.7%. Since he's never been a high-velocity pitcher without heavy name recognition, Kelly has struggled with being severely underrated year in and year out.

He's only improved over the last two seasons, and 2023 was a stellar season for the veteran. He overcame his Dodger Stadium demon, pitching a 6 1/3 inning shutout in Arizona's blowout win in game one of the NLDS. Facing elimination, Kelly struck out eight Phillies over five innings while allowing just one run in game six of the NLCS.

But his biggest performance of the season came in the World Series. In Arizona's lone win of the series, Kelly delivered a brilliant seven inning, nine strikeout performance, allowing just one run. Kelly has the poise, ability to utilize the whole zone, and the pure stuff to be a dominant pitcher. He sat next to Zac Gallen in ace status in 2023.

The projection expects the veteran to have a better FIP than ERA. Being that the D-backs play defense exceptionally well, it's a strong possibility this disparity could even out, and Kelly's ERA (and subsequent aWAR) could benefit as a result. He might not outperform his 2023 season, but he is certainly a pitcher who has proven to be a caliber above the numbers these systems have projected for 2024.

Why Kelly might underperform this projection

Kelly struggled with some injury issues in 2023. While he doesn't have a history of being injury prone, he's also not getting much younger. At 35 years old, coming off his best full statistical season in the majors, regression is absolutely a possibility. 

While his location is generally his weapon, there was a concerning rise in walks for the right-hander. Of his 30 starts in 2023, Kelly walked three or more batters in 11 of them, and his low-velocity spelled death for misplaced balls, as he was ranked in the bottom half of MLB with regard to average exit velocity and hard-hit rate.

His breaking pitches are also a non-factor, which reduces the effect of a diverse arsenal. He recorded a -4 run value on breaking balls, ranked in the 20th percentile. While his fastball and changeup are both solid, his ability to make batters miss is barely above average (58th percentile), and if batters are figuring out how to work counts and walk when facing him, he could be in for a rough 2024.

It's not out of the question to see his location (and subsequent looking K ability) regress, which is a huge part of what makes him such a good pitcher.

Summary

While these projections are expecting a significantly worse year statistically for Kelly, it's possible he'll only continue to get better alongside a bolstered starting rotation. Kelly's ability to be consistent in his year-to-year output rightfully earned him the nickname "Mainstay," for good reason. Even if there is a regression, it's unlikely we see a drastically worse season than what we've seen out of Kelly in previous years.