Merrill Kelly was an Ace and Leader for D-backs in 2023

The veteran right-hander helped lead the Diamondbacks' pitching staff and was dominant in the postseason.

This article is part of a series of player reviews for the 2023 Arizona Diamondbacks. It was a surprising and marvelous year for the team as they won 84 games to make the postseason. They advanced to Game 5 of the World Series before bowing out to the Texas Rangers. There are 54 players in all that had at least one at-bat or pitched at least one inning for the team this past season. They are being presented in reverse order of their aWAR (average WAR-Wins Above Replacement) produced, which is the average of Baseball Reference and Fangraphs WAR. These are their season stories.

Merrill Kelly had a fantastic 2023 season and has been routinely solid while eating up innings in his career / Jake Oliver

Coming off a run with Team USA in the World Baseball Classic in which Merrill Kelly started the Championship game, Kelly started a bit slower than normal. At the same time, his ERA was a strong 3.06 in the first month of the season, over 32.1 innings and six games. He walked an above-average 18 batters. He struck out 30, but the 18 walks were alarming. In four of his first six games, he walked four or more batters. The bright side is that he went 5.2 or more innings in four of the six outings. The walks and two home runs help explain why his FIP was at 4.06 indicating that he was quite lucky to have such a low ERA.

In May, Kelly completely righted the ship. He reversed his walk trends by walking just seven batters in his 31.1 innings and five starts. He pitched at least six innings four times, twice reaching seven. He struck out 39 batters and had a 2.59 ERA/2.68 FIP while going 4-0. Merrill the Mainstay was in pursuit of his first All-Star season and looked like the true second ace that the Diamondbacks needed.

In June, it was an up-down road for Kelly. While he went 3-1, the walks slowly started to creep back up with a four-piece in a start and he walked 12 in 31.1 innings over five starts. He struck out 29 and allowed only 28 hits. However, the home run bug bit him as he gave up five in this month. Only one of his starts was home run-free.  Kelly worked to a much higher 4.02 ERA and 4.72 FIP. Unfortunately, Kelly wouldn't escape June unscathed. He would develop a blood clot in his calf and would be placed on the Injured List soon after his last start on June 24th. This would end up wiping out his chance to become an All-Star for the first time.

He wouldn't return until a month later on July 25th. It was clear that the month off did wonders for Kelly. At least in terms of the command of his pitches and the strike zone. From late July to the end of August, with eight starts and 46.1 innings, Kelly pitched to a workhorse-like 3.50 ERA and a 4.14 FIP. While the home runs were still an issue, giving up seven, which led to his worst FIP, he walked only 15 batters. He struck out 49 hitters and gave up only 46 hits. He proved he was the most reliable member of the team's starting rotation. In every outing, he worked at least five innings while going six or more in five of them.

As the Diamondbacks made a fervent push for the playoffs in September, Kelly saved his best for last. While the walk issue came back with an eye-popping 17 of them in just 36.1 innings, he worked around them. He allowed only 26 hits and 13 runs in his six starts. He struck out more than a batter an inning with 40 of them. His ERA was a sterling 3.22 and his FIP was a better 3.53. This was because he got past his home run issues. He allowed only three of them. Once again, Kelly pitched at least five innings in every start. He went 5.2 or more in four of them.

It was a career regular season for Kelly. Yet, the best was to come as he became a dominant ace in the postseason. He helped lead the Diamondbacks' pitching staff to their best performances as the team made a surprising run to the World Series. In Kelly's first start against the Dodgers, he shut them down in Game 1. He pitched 6.1 innings and gave up only three hits, two walks, and five strikeouts. In the NLCS, Kelly struggled in Game 2, but still pitched 5.2 innings despite allowing four runs. He walked three but struck out six and gave up only three hits. Instead, it was the home run ball that sank him as the Phillies blitzed him for three.

However, Kelly would get his revenge on them in Game 6. In a must-win game for the D-backs, Kelly allowed just a run in five innings in a game in which he arguably could've gone deeper. He struck out eight against three walks and only allowed three hits. This performance allowed the D-backs to set up their bullpen how they wanted and to win Game Six. 

In the World Series, on the game's biggest and brightest stage, Kelly had the best game of his career. He pitched seven innings in Game 2 allowing just three hits and one run while walking none and striking out nine batters. This performance got the D-backs their only win in the World Series. It will go down in D-backs lore that Kelly had one of the best postseason starts in team history. In total, over four starts and 24 innings, Kelly had a 2.25 ERA and 28 strikeouts.

Digging Deeper into the Statistics

Merrill Kelly proved that he was not just a workhorse starting pitcher, but was capable of being an ace-level pitcher in his Age 34 season. Of his 30 starts, Kelly gave up two or fewer earned runs in 19 of them. He only gave up more than four runs in three starts. Plus, he saved the bullpen a lot of innings. Kelly pitched more than six innings in 19 starts. 

That kind of length to go with his strong run prevention made Kelly one of the best starting pitchers in the National League. He was a throwback to the days of old in which pitchers routinely pitched deep into games. That kind of performance saved the Diamondbacks' season as they struggled to fill out the final three spots in their rotation.

Kelly was dominant against both-handedness batters. He allowed just a .658 OPS to right-handers and a .683 OPS to lefties. It would be remiss to not point out that Kelly struggled on the road as compared to pitching at Chase Field. The veteran starting pitcher pitched to a sparkling 2.59 ERA over his 15 home games and 93.2 innings. He walked 36 and struck out 106. Plus, he gave up only 60 hits.

On the road, Kelly was a good pitcher, but not an ace-caliber. He had a 4.07 ERA in 15 games and 84 innings. He struggled to work deeper into games, albeit three of those starts involved him giving up a combined 19 earned runs in only 15 innings. Take those three starts away and this is a different conversation. Still, they happened, and he gave up 83 hits, 11 home runs, 33 walks, and struck out only 81 batters. Kelly was more comfortable pitching at home than on the road.  

Merrill Kelly had a 132 ERA+, 100 league average, and allowed the second-lowest 1.0 home runs per nine innings of his career. His Wins Above Average was a career-high 2.3. His xERA at 4.13 indicates his 3.29 ERA was a tad lucky, but not by a large margin. That's because while his FIP is 3.85, his xFIP was 3.83. This would indicate that while he was lucky, the results mostly fell in line with what was expected albeit fewer earned runs than expected. The difference can be written off as some clutch pitching and the excellent defense behind him saved more than a few runs.

Some interesting stats are that Merrill Kelly pitched a Quality Start in 60% (18) of his starts. His extra-base hits%  was a career-low 7.3%. He had a career-high strikeout rate of 25.9%, but he walked batters at a career-high 9.6%. Batters stole just 13 bags off of him in 17 attempts, good for a 76% rate. 

2024 Status and Outlook

Merrill Kelly is in the middle of an extension he signed with the Diamondbacks ahead of the 2022 season. It's a two-year deal with an option. The first year was in 2023. This means that Kelly is on the books for $9MM in 2024 with a team option for 2025. That option will likely be picked up. This gives the Arizona Diamondbacks control of their veteran starting pitcher for the next two seasons in what will be his Age 35 and 36 seasons. 

As for the 2024 season, Merrill Kelly will slot into the starting rotation as the No. 2 pitcher behind Zac Gallen and ahead of Eduardo Rodriguez. If he can replicate his season from 2023 and remain healthy, it's quite likely that Kelly will make his first All-Star team. The Diamondbacks will be relying on Kelly to be the starter he was this year once again as they make another strong push for the playoffs in 2024 to defend their National League crown. There's nothing in his stats that would indicate that Kelly is going to experience a drop-off in play, even despite his somewhat older age. Merrill the Mainstay will be back to handle a large innings load in 2024.

Diamondbacks 2023 Top 54 Player Reviews Links Hub

Merrill Kelly Dominant as D-backs Even Up World Series