6 free agent targets to bolster the Diamondbacks bullpen

Nov 16, 2022, 9:55 AM | Updated: Dec 5, 2022, 4:06 pm

If not the greatest weakness, the bullpen was at least the most glaring on the Arizona Diamondbacks roster in 2022.

Assistant general manager Mike Fitzgerald addressed this issue in October and suggested that an approach shift is in order.

“[We have to be] honest with ourselves in terms of how we’ve tried to approach solving that problem,” Fitzgerald told Arizona Sports’ Wolf & Luke on Oct. 5.

The D-backs had 46 games in 2022 where they entered the sixth inning no worse than tied and ended up losing. For a team that missed the postseason by 13 games, that’s certainly an easy stat to point at and call “the reason” the season ended after 162 games.

In 2022, the Diamondbacks relievers had an MLB-worst -0.7 wins above replacement.

They also ranked 25th with a 4.58 ERA, 29th with a 4.39 FIP, and 30th in strikeouts-per-nine innings, strikeout rate and SIERA — an ERA estimator similar to FIP that values strikeouts more and tries to factor in the quality of balls put in play.

They also ranked 29th in average fastball velocity and groundball rate.

Long story short, a lot went wrong in 2022 and Arizona needs to have a better bullpen in 2023 if the franchise has postseason aspirations.

For that, here are six targets — three righties and lefties apiece — that make sense for the Diamondbacks in free agency.


D-backs right-handed relievers posted a 5.03 ERA in 2022 with a .780 OPS.

For reference, there were 130 qualified hitters in 2022 — let’s call opponents against D-backs right-handed pitchers “Qualified Hitter 131.”

Qualified hitter 131 ranked 52nd in OPS in 2022, ahead of All-Stars like Ty France, Corey Seager and Ronald Acuna Jr.

Craig Kimbrel

(AP Photo/Ross D. Franklin)

Let’s have some fun to start, shall we?

Yes, the likelihood of the D-backs landing Kimbrel is probably not the highest. However, there would never be a better time to try.

This past season represents the third non-vintage year for Kimbrel out of the past four. That being said, for the Los Angeles Dodgers, he still had 24 saves-plus-holds out of 29 opportunities, despite the 3.75 ERA.

He also struck out 27.7% of batters faced and had the best groundball rate of his career since 2015 with the San Diego Padres.

Yes, there are certainly red flags. For example, he basically stopped striking hitters out in the second half of this past season. While he still had a 3.10 ERA after the deadline, the drop to 7.76 K/9 is alarming.

He’s also coming off the worst season of his career for his fastball in terms of velocity.

While 95.8 mph on average is still good for 83rd percentile in the league, it’s becoming clear the right-hander is heavily reliant on having an explosive fastball.

To further expand, he averaged 97.2 mph on his fastball with the Chicago Cubs in 2021 and had a 0.49 ERA with 23 saves in 25 opportunities.

After getting traded to the White Sox, his average fastball dipped to 96 mph and his ERA ballooned to 5.09 in 24 outings.

Would signing the 34-year-old Kimbrel possibly be taking a swing at a regressing future Hall of Famer? Yes. However, they’ve taken chances on older, lower-ceiling options in the past. Why not take a chance on someone of Kimbrel’s status?

Trevor May

May’s time in Queens was up and down, to say the least.

In 2021, he posted a 3.59 ERA and struck out 31.2% of batters.

However, he got off to a nightmarish start to 2022 and then missed three months to injury. He rebounded with a 3.24 ERA and 2.75 FIP in his final 18 outings.

Overall, he posted a 5.04 ERA in 2022 but had a FIP of 3.87 and SIERA of 3.29 while still striking out 27% of batters faced.

That said, he’s 33 years old now and coming off a season with a three-month absence with a triceps injury. That could potentially scare some teams away, thus opening the door for GM Mike Hazen and Co. to land a quality arm with a 3.54 ERA and 11.9 K/9 since the start of 2018.

Michael Fulmer

It’s been a tale of three careers for the long-time Detroit Tiger and short-time Minnesota Twins right-hander.

He won Rookie of the Year and finished 10th in Cy Young voting in 2016, going 11-7 with a 3.06 ERA and 3.76 FIP.

In 2017, he made the All-Star team and saw his FIP improve to 3.67 despite his ERA jumping to 3.83.

He struggled in 2018, had knee surgery that September, then got Tommy John Surgery in 2019 and didn’t pitch at the MLB level again until 2021.

Since returning to the majors, he’s made 119 appearances — only four starts — and has a 3.17 ERA, a 3.51 FIP and 134 strikeouts in 133.1 innings.

He’s a talented arm, even though he isn’t the prototypical high-leverage reliever that strikes out a third of his batters faced.


The trio of Joe Mantiply, Kyle Nelson and Caleb Smith combined to post a 2.56 ERA, so it’s reasonable to assume adding a southpaw won’t top the priority list.

However, Smith was designated for assignment Tuesday, and adding quality left-handed arms only raises the bullpen’s ceiling as well as improves depth.

Matt Moore

(AP Photo/Mark LoMoglio)

Moore was a revelation with the Texas Rangers last season.

Once an All-Star and Cy Young top-10 finisher, Moore struggled for years to maintain consistent success as a starter, much like the aforementioned Fulmer.

In 2022, he finally settled into a full-time role as a reliever and he was dominant. Among left-handed relievers with at least 25 innings, Moore was tied for ninth in ERA, seventh in slugging percentage against and 20th in strikeout rate.

After seeing a decrease in velocity between 2019 and 2021, Moore’s fastball averaged 94 mph for the first time since he averaged 94.8 mph as a 23-year-old rookie in 2012.

Joely Rodriguez

If you want intrigue, Rodriguez is about as intriguing a lefty option as there is on the market.

With a 4.47 ERA this past season, he’s on par with last year’s D-backs bullpen. However, his peripheral numbers — ERA estimators — suggest he’s due for some serious positive regression.

Last season, he had a 3.23 FIP and 3.54 SIERA. Both would fall into Arizona’s top-four relievers (minimum 20 innings).

The 31-year-old southpaw has turned into a journeyman despite debuting in 2016. He’s made at least 20 appearances for four different franchises.

The COVID-19 year was Rodriguez’s breakout, albeit in 12.2 innings. He pitched to a 2.13 ERA and struck out 17 of the 52 batters he faced. Since then, he’s posted ERAs of 4.66 and 4.47, but his underlying data is the eye-catcher.

That and his 56.5% career groundball rate.

D-backs pitchers held opponents to a .473 OPS and just 39 extra-base hits last season on ground balls, which was 10th in the majors.

If they were to go after a lefty, Rodriguez makes a lot of sense.

Adam Kolarek

Rounding out the list is the veteran, Kolarek.

At the surface, he’s probably a minor-league deal with a roster invite to spring training and his skillset doesn’t exhibit much of a change in approach — like Fitzgerald alluded to at the beginning of the offseason.

Last season, Kolarek posted a 4.58 ERA and a 4.70 FIP. However, his groundball rate was 69.5% and had an average launch angle of 0.5 degrees.

If you’re not striking hitters out, your best course of action is likely keeping the ball on the ground. Kolarek is very good at generating ground balls

In his 170 career outings, Kolarek has yielded 464 batted ball events. In those events, only 165 were fly balls or liners.

As a minor league deal, he makes a lot of sense for the D-backs.

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