Relief pitching is one of, if not the most volatile things in baseball. Good relief pitching is so common you can get it from the minor leagues and waivers just as easily as you can find them on the trade market and free agency. All you really need is a good pitching lab and you can develop anyone with plus stuff to be an effective member of your bullpen. So, the question is, why do some teams deal valuable assets for a one inning, 15 pitch player? Is it worth it?

In my opinion, it is not. There are a lot of homegrown/minor league/waiver acquired star relievers that their teams got for cheap. For example, Kenley Jansen (Dodgers), Devin Williams, Ryan Helsley, and Paul Sewald were low profile acquisitions/draft picks. Look how productive they’ve been throughout their time in the majors. Their teams acquired them without having to give up any assets/spend much money and they are a testament to their ballclub’s pitching development. All clubs can do this. It’s not about who has more money or who has less money, it’s about how committed a ballclub is to developing good major league players. Now let’s look at some more notable relief pitcher moves in recent history and review the outcomes.

Edwin Diaz

One of the biggest relief pitcher trades in the past decade or so is the Edwin Diaz trade between the New York Mets and Seattle Mariners. Here’s the full trade:

New York: INF Robinson Cano, RHP Edwin Diaz, $20 million

Seattle: OF Jay Bruce, RHP Anthony Swarzak, RHP Gerson Bautista (NYM #29), RHP Justin Dunn (NYM #3), OF Jarred Kelenic

At the time of this move, Seattle was rebuilding, having already shipped out the likes of Jean Segura and James Paxton. The Mariners offloaded a productive but expensive Robinson Cano along with major league saves leader Edwin Diaz for a package centered mainly around Dunn. However, the most promising piece from that package turned out to be now-former Mariners top prospect Jarred Kelenic. Kelenic has struggled in the majors so far, posting a 62 wRC+ since his debut in May 2021. I do believe there still is time for him to become a solid everyday outfielder for the Mariners, but each and everyday more people are focused on Julio Rodriguez and forgetting about Kelenic. For New York, they acquired the aging Cano, who has put up one good year for them and has since been DFA’d. Diaz, on the other hand, has rebounded after a rough first season with New York, where he posted a 136 ERA- and a 3.07 xFIP, to become the best relief pitcher in baseball. Since 2020, he has posted a 2.29 xFIP and has proven that he has the best stuff in the game. Overall, this trade is an easy win for the Mets, however it wouldn’t be incorrect to call this trade risky at the time considering the potential that both Dunn and Kelenic showed.

NYM: A-

SEA: C+

Ryan Pressly

This trade in no way holds the same magnitude as the Edwin Diaz trade, but it certainly is a trade worth looking at. Here’s the full trade:

HOU: RHP Ryan Pressly

MIN: RHP Jorge Alcala (HOU #7), OF Gilberto Celestino (HOU #23)

In my opinion, this trade is a lot closer than the Edwin Diaz trade. Gilberto Celestino is still young and has some potential in him to be close to a league average hitter. He’s posted a 91 wRC+ so far this season and has been a good defender. He doesn’t hit the ball very hard though, which is a concern because now he is relying on a high BABIP (batting average on balls put in play) to get on base. He has posted a .346 BABIP this year so you could say he’s gotten a bit lucky in batted balls. Alcala appeared in 59 games last year and was in the 96th percentile for both fastball velocity and chase rate. He clearly has good stuff to become a serviceable reliever in the future. Alcala posted a 3.54 xFIP in 2021. For Houston, they acquired someone who is now one of the best relievers in baseball in Pressly. He was very solid in Minnesota but has taken his game to a new level. In 2021, he has made his curveball his main putaway pitch compared to his slider from 2020. His curveball produces a 41% whiff rate and is in the 100th percentile in curveball spin, with an average RPM of 3224. Pressly has been the main staple of this Astros bullpen and should continue to be for the next few years. Overall, I would say Houston wins this trade but Minnesota did not do bad at all.

HOU: A

MIN: B+

Liam Hendriks

The last one I want to talk about is not the Liam Hendriks trade but the Liam Hendriks signing by the White Sox. Prior to the 2021 season Chicago signed Hendriks to a 3 year deal worth $54 million and carrying an AAV of $18 million, making him the highest paid relief pitcher in baseball. The contract is well deserved by Hendriks, seeing that he posted a 2.07 xFIP with Oakland in 2020. For quite a few years, Hendriks has been one of the best relievers in baseball and it’s set to continue for a few years down the line. Hendriks is prone to give up hard hit balls as he ranks in the 5th percentile of average exit velocity. However, he has really good strikeout stuff, ranking in the 99th percentile for whiff% and 93rd percentile for chase rate. Was the contract an overpay? Slightly, but Chicago gave him a higher AAV so they wouldn’t be strapped to him for too long. Is Hendriks a good player and deserving of the contract? Yes, there aren’t many guys out there like him. Overall, this was a decent move by Chicago to solidify their bullpen and there aren’t too many problems with it.

Conclusion

Even though the trades I aforementioned have the team acquiring the reliever winning, I just do not think it is worth the risk of giving up assets with potential. Relievers are so volatile that one year they could be lights out and the next year completely awful. Although there are some situations where it is appropriate to trade promising assets for relievers, I do not think they will be worth it. A good pitching development can go a long way for a team’s bullpen and rotation, so that’s why teams like the Dodgers with Mark Prior and Yankees with Matt Blake have been able to advance so far ahead of the rest of the field in almost every single pitching department. This also has an effect on the relief pitcher free agent market. I almost never think it’s worth it to give relievers more than $12-14 million per year in free agency. Take a look at the contracts of Emmanuel Clase and Aaron Ashby. Two very good relief pitchers who signed deals with term and a lesser AAV. As the business of baseball progresses and perspective on stats and productivity shift towards analytics/saber metrics, the Ashby and Clase contracts will be the prototype to any team looking to lock up their star young relief pitchers for a while.