Can Ryan Thompson Return to Elite Form For the D-backs?

The sidewinding reliever struggled down the stretch of 2024, and his projections are somewhat modest.

Sep 10, 2024; Phoenix, Arizona, USA; Arizona Diamondbacks pitcher Ryan Thompson (81) makes the play for an out against the Texas Rangers in the seventh inning at Chase Field. Mandatory Credit: Rick Scuteri-Imagn Images / Rick Scuteri-Imagn Images

In our journey across each individual player projection of the 2025 Arizona Diamondbacks, we reach a key contributor of the 2023 pennant-winning team, and a stalwart of the D-backs' bullpen in Ryan Thompson.

These projections are a composite of ZiPS and Steamer, prorated to our own playing time projection.

RHP Ryan Thompson, 32

Ryan Thompson stats and projection / Alex D'Agostino / Diamondbacks On SI

Right-handed sidewinder Ryan Thompson has been an invaluable member of the Diamondbacks' bullpen. A late-2023 acquisition, Thompson immediately became a strong contributor to Arizona's World Series run.

In 2024, he began the season high, but lapses in command, coupled with some poor outings ballooned his ERA from an elite number to one that was more moderate, though still very solid.

Why Thompson might outperform projections

Thompson has been one of the most effective arms in the D-backs' bullpen since he arrived. As with any reliever, ERA and other metrics can be quite volatile, and a poor outing or two can skew the season outlook as a whole.

So it's a bit of a surprise that the projections expect a near half-run regression in terms of ERA, and a mere 0.4 aWAR output.

In 2024, Thompson's 3.30 FIP backed up his 3.26 ERA. He posted nearly a full win of aWAR over 66 innings, despite a very rough stretch in August and September.

While he's never been the most strikeout-heavy pitcher, he's been a consistently excellent ground ball arm, with a 99th percentile ground ball rate (62.7%) in 2024.

That number may not be sustainable, but it stands to note that Thompson was able to carry his excellence through the first four straight months of the season.

As the season waned, so did his command, and he began to get hit harder. Despite that, he still finished with an excellent 0.68 home runs per nine.

While it might not be realistic to expect a sparkling ERA out of the righty, he has shown the ability to have extended, consistent, backed-up success on the mound. There aren't many reasons (barring injury) to expect him to take a major step back in 2024.

Considering the consistency with which he's been effective, and the hope of an added bullpen arm to take a few appearances off Thompson's plate, he could easily avoid that late-season fatigue slump and carry excellent numbers well above his projection to end the year.

Why Thompson might underperform projections

Simply put, if Thompson pitches as he did the final two months of 2024, he might be in trouble.

With an already low-velocity arsenal, mainly centered around a sinker and slider, Thompson's weapons are based on his ability to command them, as well as his unconventional sidearm delivery and the movement on his pitches.

What began to happen down the stretch in 2024 was a decline in two of those factors, which led to much harder contact.

Thompson was in the bottom 20% of MLB in hard-hit % and average exit velocity, and both his strikeout rate and whiff rate were well below average.

That's not necessarily a knock on a player who has sustained excellent success as a groundball pitcher, but it does show the delicate balance of his effectiveness.

If Thompson's movement, velocity or command decline any further, his stuff quickly becomes batting practice, which would easily lead to an inflated ERA, given the volatility of relief numbers.

He's also prone to the occasional blowup outing, so while these projections aren't sky-high, one or two poor outings could set Thompson up to finish below them, even if he does have an overall effective seasos.

Summary

Thompson will still slot into the high-leverage group of D-backs relievers, and for good reason. The sidewinder has managed to sustain success as a ground ball pitcher, while coming up big in many huge situations for Arizona.

If he takes a step back in number of appearances and innings, he will have a good chance to avoid that late-season fatigue and maintain his command, leading to another excellent year in the D-backs' bullpen.

But if he begins to lose some of his movement and command, as was seen late in 2024, he might set himself up for an uphill climb if he wants to overcome projections that already expect regression from the righty.

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