
I’ve seen a number of comments on social media recently, saying things like the D-backs have the best bullpen in the majors, or that this is the best bullpen in franchise history. However, if you look at the raw metrics, there’s not much evidence to support either statement. We’ve talked (a lot!) before about Mike Hazen’s issues with regard to building bullpens. Most recently, just after Opening Day this season, when our relievers had an ERA of 9.00. It looked like this was going to be another in a long series of bullpen disasters. After all, from 2017-2025, the team’s relievers ranked 24th for ERA, 27th for xERA, 25th for FIP and dead last for fWAR.
And those figures include a largely-inherited 2017 bullpen which was above average, ranking 5th by ERA. Since then? Well, 2017 was the last time our bullpen ranked in the top half by fWAR. The chart below shows where the team’s relievers have ranked in those metrics each year, since Mike Hazen took over. It comes from my end-of-season review last November, after a campaign where the team tied a franchise high with 28 blown saves. It probably would have been worst still, save for the unexpected resurrection of Shelby Miller, who went from non-roster invitee in spring training, to everyday closer by May. Anyway, here’s the graph.

Dismal, across the board. Now, to 2026. There’s no denying, the D-backs’ bullpen has been better this year. Specifically, here are their rankings for those four metrics, going into yesterday’s series finale in Kansas City (as are all numbers quoted in this article): ERA 15th; FIP 14th; xFIP 16th; fWAR 14th. Now, it’s a clear improvement, considering the team hasn’t been in the top half of MLB for any of those figures since 2019. But they’re all relentlessly middle-of-the-pack. Not “best in baseball” level, and nowhere near “best in franchise history” level. For the latter, I’d personally go with the 2012 bullpen, who had a 3.28 ERA, but will hear arguments for 2003.
So, why are fans so deliriously happy with the 2026 bullpen – arguably, above what it merits. I think there’s a few reasons, and there are some metrics where the bullpen has performed extraordinarily well. But to start with perception. It’s partly that the bullpen has, as documented above, been so utterly terrible in the 2020s. Last winter, I wrote, tongue in cheek, how it’s “beginning to feel like I’m in a toxic relationship with the D-backs bullpen.” And in one of those, you’ll latch onto any positive signs, believing them to be more important than they are. Compared to what we’ve been through, simple mediocrity is a huge improvement. Our relievers have just stopped punching us in the gut as often. Yay. 🙂
Another factor, is the sharp difference between the A- and B-bullpens. The good guys have been very good. We have four relievers – Brandyn Garcia, Juan Morillo, Jonathan Loaisiga and Taylor Clarke – who have thrown 40+ innings with an ERA below 2.50. No other team has that many. The Padres are the only side with more than two, and fully half the league have had nobody in that category for their bullpen this season. Arizona’s overall figures are hurt by the tail. They’ve used ten genuine relievers with an ERA worse than 4.91 this year – I pick that figure, as it’s Ildemaro Vargas’s 2026 ERA. Those ten have combined for 121.1 IP at an ERA of 7.21.
But the tip of the spear has been good – and, unlike the rest of the roster, generally healthy. I’d call this testament to a great job done by Torey Lovullo, in conjunction with the information provided to him by the front office, to avoid over-taxing any one arm. We have four relievers (Clarke, Morillo, Loaisiga and Kevin Ginkel) who are all over sixty appearances and on pace for sixty-five plus this year. The Blue Jays are the only other team currently to have four relievers at over sixty games. The D-backs have never had four pitchers appear 65 times in a season. It feels as if adjustments were made after last year, where we saw the seasons of our three main closers, all end in elbow surgery.
This year’s bullpen has also been great when needed. Here’s the stat which shows this most. They are 66-0 when leading after eight innings, the only perfect score in the National League. Say what you like about Paul Sewald – now up to nine scoreless appearances for Toronto, incidentally – but he got the job done when given a lead. If the team can get through these final couple of weeks without losing that unblemished record, it’ll be the first time Arizona has done so since 2011, when they were 84-0 [That 2003 squad I mentioned above were also perfect when leading after eight]
Now, there have still been blown saves, as with any relief corps. But only seventeen, a large improvement on 2025’s record number. And the team still won the game most of the time (nine of the seventeen). As we saw on Tuesday in Kansas City when both Morillo and Blake Walston were charged with a blown save, nobody really cares much if you prevails in the end. Since June 21, there has been just one blown save by Arizona which led to a loss: Loaisiga against the Pirates on July 27. It’s hard to get annoyed with a segment of the team that has done very little to cost the team games in the second half.
But perhaps the number which does most to explain the positive perception of the D-backs bullpen, is Win Probability. They currently sit, for the year as a whole, at +818%, the second-best figure in baseball behind the Braves (a startling +1088%). That’s the highest figure in Arizona since 2007’s +913%, and with 16 games left, they still have a shot at chasing that down. Put simply, this year’s model has had a hugely positive impact on the team’s chances. It’s the biggest bullpen turnaround in franchise history, already representing an improvement of more than a dozen wins compared to last year, when they ended the season at -404%.
There will be significant work for Hazen this winter, with three of those “core four”, Ginkel, Loaisiga and Clarke, becoming free agents. But in Morillo, Garcia and Justin Martinez, the foundations are there for the longer term. Has Hazen finally cracked the “secret sauce” of building a bullpen on a budget? Or was this just a year where the ebb and flow of reliever volatility, finally worked in his favor? We’ll see next season. If it’s the latter, let’s just hope that volatility can be staved off for a few more weeks!


















