This article is part of a series chronicling the individual seasons of players who appeared for the Arizona Diamondbacks in 2024.

Reviews for players who still have rookie eligibility for 2025 will appear in our prospect season reviews. Players are presented in the reverse order of their aWAR, an average of Baseball Reference and FanGraphs WAR.

2024 Contract status: Arbitration, $1,350,000

When the Diamondbacks signed right-handed reliever Ryan Thompson to a minor league deal midway through the 2023 season, no one, except perhaps general manager Mike Hazen, had any idea of how impactful the move would be.

Thompson brought consistent stability to Arizona’s bullpen, immediately stepping into a high-leverage role, with his devastating arsenal and confounding sidearm angle baffling opposing hitters and pitching to a stellar 0.69 ERA with the D-backs in the regular season.

When 2024 began, Thompson slotted back into his high-leverage role. And for the first several months, the righty was just as dominant as he had been the prior season. He allowed just three earned runs over his first 22 appearances, pitching to a 1.14 ERA through May.

He was quite effective in June as well, up until June 28, where he gave up three hits, a walk and a home run, leading to a three-run day against the Oakland A’s. He settled back in quickly enough, giving up just two runs in July, and giving up just a .143 average for the month.

Unfortunately, like many of the D-backs’ other arms, his effectiveness took a hit as the latter months began. And, as with much of Arizona’s pitching staff, once Paul Sewald began to stumble out of his closer’s role, the rest of the high-leverage arms lost their groove.

It was oddly definitive for Thompson when this began to break down, correlated directly with Sewald’s removal from the ninth inning.

On July 31, Sewald had loaded the bases with a thin lead on the Washington Nationals. To avoid disaster, manager Torey Lovullo pulled his closer, and turned to Thompson to finish the job. It was a nail-biting finish, but the sidewinder sealed the win, and the sweep.

Two days later, Sewald was officially demoted, and Thompson’s struggles began to take hold. He allowed a run in his first three outings to begin August (including a blown save), and while the right-hander’s ERA was still an objectively excellent number at 2.30, it had more than doubled in just over a month.

He gave up just one unearned run over his next three outings, but on August 16, he suffered a blow to his confidence.

Facing the Tampa Bay Rays, in what was a sloppy series, filled with errors, the normally lockdown reliever gave up a walk and four hits. While a couple of them were cheap hits that could or should have been outs, Thompson only managed to record two outs, giving up three runs and giving up the lead.

He then delivered six more scoreless appearances, though they did look more labored. His pitch counts saw some spikes, and his command looked less sharp than it normally had been, with location mistakes on his slider and sinker frequently flying way outside the zone.

After a two-run outing against the Los Angeles Dodgers to close down the month, Thompson’s August ERA was an unsightly 6.17. Unfortunately for both he and the D-backs, September would open with his worst outing of the season, as he gave up four runs on four hits and a walk in San Francisco.

His once-sparkling ERA ballooned to a still-respectable but closer to average 3.26 as the season closed, with September marking his second straight 6.00+ ERA month.

Now, the illustration of these late struggles aren’t to say his season should be looked at negatively. Thompson was, by all metrics, a very effective arm for the D-backs, and, in many cases, he was asked to carry a major part of the bullpen workload.

The sidewinder eclipsed his previous season-high innings by 23.2, pitching 66.1 innings over 67 appearances in 2024. His FIP was 3.30, suggesting he pitched about as well as his results showed, though, as a pitcher who thrived on weak contact, he was susceptible to plenty of cheap hits, and occasionally bitten by poor defense.

Both his slider and sinker, two of his primary soft-contact pitches, began to lose some of their movement. Fatigue appeared to be taking its toll on the righty, and some poor luck made it a bit of a difficult stretch.

That said, the D-backs’ bullpen would certainly have been in worse shape without Thompson’s efforts. He may have struggled as the year progressed, but remains one of the most important members of Arizona’s relief corp, dating back to his contributions to 2023’s World Series run.

2025 Contract status: Arbitration, estimated $3,070,000 per Spotrac

The big right-hander is still arbitration eligible, and is estimated to earn $3,070,000 next season. There’s very little doubt he’ll return to the D-backs in 2025, and will likely retain his spot in higher-leverage situations, even if an addition is made.

Despite being 32 years old, Thompson won’t be a free agent until 2027. Barring injury or severe deterioration, Arizona will be happy to see the big sidewinder back on the mound at Chase Field next season.

With an off-season to recover, and hopefully a more permanent ninth-inning solution, it’s quite possible Thompson pitches closer to his 2023 and early-2024 self than his poorer recent months.