The first surprise of the offseason arrived this week when the Orioles declined the $4 million option in Danny Coulombe’s contract, making the reliable left-hander a free agent.

After his arrival ahead of the 2023 season, Coulombe went from an afterthought to a stalwart in high-leverage situations. Even with a lengthy absence this year because of elbow surgery to remove bone chips, Coulombe compiled another standout season.

But the Orioles, it appears, made the decision on Coulombe by projecting how the 35-year-old may pitch in the future rather than relying on what he produced in the past.

The past, of course, is complimentary to Coulombe. In two seasons in Baltimore, he combined to throw 81 innings with a 2.56 ERA and 0.95 WHIP.

The future is hazier.

“Sometimes, you make a decision not to kick off your offseason with exercising an option, but you remain in position to stay in touch with a really good player,” general manager Mike Elias told reporters at the GM Meetings on Tuesday. “Danny’s done a ton for us, been enormously successful the past couple years and we really enjoyed having him, and he’s somebody that we’re going to want to continue talking to throughout free agency, as long as that lasts.”

Money doesn’t appear to be a factor in the move when considering that Baltimore exercised $8 million options for first baseman Ryan O’Hearn and right-hander Seranthony Domínguez.

Instead, there are a couple of key analytical measures and one roster construction consideration that may have played a role in why Baltimore opted against bringing back one of its best relievers.

A decrease in velocity

Coulombe has never been a fireballer, and he doesn’t need to be. The southpaw’s four-seam fastball and sinker served more as setup pitches throughout his career for his cutter, sweeper or knuckle curve, rather than blow-away offerings on their own.

But, after Coulombe returned from his elbow injury in September, there was a noticeable decline in his average fastball velocity. In June, his sinker and four-seamer each averaged higher than 91 mph. By September, they were at 89 mph. His cutter, sweeper and knuckle curve also dipped by about 2 mph each from pre- to post-surgery.

Coulombe only threw 3⅔ innings upon his return, and that was without a full ramp-up period. Given more time, Coulombe’s velocity could have increased once more. And, even with lower velocity, Coulombe found success. He didn’t allow a run in his final four outings of the regular season.

But over the course of a season, should the velocity not return, Coulombe’s effectiveness might wane.

Lesser ‘stuff’

The Orioles are a data-driven operation. Many of the data points surrounding Coulombe are positive — a 29.9% strikeout rate, 4.7% walk rate, 0.67 WHIP — and they are reflective of his superb season. But there’s one, Stuff+, that leaves something to be desired.

First, an explanation of what exactly Stuff+ is. The metric looks at the characteristics of a pitch and ignores the result. It takes into account the release point, velocity, vertical and horizontal movement, and spin rate. In short, it can quantify how deceptive or difficult to hit — or nasty — a pitcher’s arsenal is.

Coulombe hasn’t needed rave reviews in Stuff+ to find success in his career, but it’s worth noting that his Stuff+ rating went from 107 in 2023 to 80 in 2024, with 100 being league average.

Two of the major reasons Coulombe received an above-average Stuff+ rating in 2023 were that his fastball was rated at 118 and his sinker received a 127, according to FanGraphs. They joined positive ratings for his sweeper (113) and knuckle curve (105) and made him one of the “nastiest” relievers on the Orioles.

In 2024, partly because of a velocity dip, Coulombe’s fastball and sinker ratings plummeted. He received a 75 Stuff+ rating for his four-seamer and an 8 for his sinker (not a typo) — far below league average. His sweeper (106) and knuckle curve (109) were still well regarded analytically, but at a certain point, without fastballs that proved deceptive, hitters can afford to lay off the more difficult off-speed offerings.

The Orioles are set to have a lefty-heavy bullpen

The roster construction of the bullpen remains to be seen, but as things stand, there are as many as four left-handers in what tends to be an eight-man group. Three are near locks: Keegan Akin, Cionel Pérez and Gregory Soto. Additionally, the Orioles added 32-year-old minor leaguer Luis González to the 40-man roster this week.

González is a former top-30 prospect who excelled abroad before returning to the U.S. with a strong season at Triple-A Norfolk. What stood out about González is his strikeout-to-walk ratio of 5.92.

Given that makeup, the front office could have confidence in the stable of left-handed relievers already under team control.