Ranking the Top 5 All Time Diamondbacks Relievers

This table is ranked by RA9-WAR. Brad Ziegler's combination of ERA- and innings pitched makes him a clear leader in run prevention. His IRS% is also well below league average, although not quite the best.  Byung-Hyun Kim and Archie Bradley have essentially the same ERA-, separated by just a point, but Kim's higher workload puts him above Bradley in RA-9 WAR.  Jose Valverde and J.J. Puts round out the group. 

Situational Pitching and Leverage 

The below table takes a look at two aspects of situational pitching.  Traditional "Save percentage"  A save chance can occur before the 9th inning and if a pitcher comes into the game in a save situation and preserves the lead before passing on to the next pitcher then he cannot get a save. But he can be credited with an unofficial stat called a hold.   Most outlets that show "save percentage:" don't include holds, which  therefore distorts the save percentage, as he's charged with a blown save if he gives up the lead but doesn't get credit when he preserves the lead prior to the 9th inning.  Whether the pitcher is asked to preserve the lead before, during or after the 9th inning is a manger's decision. What I show below is the total number of save situations, the total number of saves + holds, which gives us a true save percentage. 

The other piece is high leverage pitching. For this we look at two metrics, WPA, or Win Percentage Added. Fangraphs describes WPA as follows: 

Win Probability Added (WPA) captures the change in Win Expectancy from one plate appearance to the next and credits or debits the player based on how much their action increased their team’s odds of winning. 

Here once again we see Ziegler atop the table. He and Valverde have the highest True Save Percentage, and Ziegler blows away the field in WPA. This in part goes back to the first table above. Note the 184 inherited runners for Ziegler. He was constantly put in high pressure situations in the 7th and 8th innings with men on base, and later in his D-backs career he was closing, which is high leverage in and of itself.  Kim's WPA total is higher than Putz as he not only closed but had to deal with three times as many inherited runners.  Putz was a high percentage closer however.  Bradley lags the table somewhat in True Save Percentage, but his volume gives him higher WPA

FIP (Fielding Independent Pitching)

Fielding independent pitching is a metric that only looks at the the things the pitcher has less control over in theory. Those are strikeouts, walks, and home runs. The actual number of runs allowed, or any balls in play that may be affected by the defense are stripped out. It's supposedly a truer measure of the pitcher's talent. It's the foundation of Fangraphs' flagship WAR metric, (separate from RA-9 WAR which includes runs allowed).   Four of the five pitchers here rank very strongly in FIP, roughly 25% better than league average,  thanks to excellent strikeout totals.  

Ziegler lags in FIP  because he was not a big strikeout pitcher. Proponents of FIP based WAR might ding him heavily for his lack of strikeouts. But he had one superpower that more than made up for it and was anything but a fluke. Ziegler had a high ground ball rate and an uncanny ability that lasted throughout his career to induce double plays.  The league average double play per opportunity rate is generally around 10-11%.  Ziegler more than doubled that with a career 21% DP rate. The other pitchers on this list were all around or below league average in this category. 

Final Ranking

#1: Brad Ziegler was the best reliever in D-backs history. With a submarine delivery he was able to throw strikes, induce weak contact, and induce double plays. He was the go to high leverage guy and produced in those situations more than any other. 

#2: Byung-Hyun Kim was another submariner who had tremendous stuff and swing and miss ability. His regular season dominance was a key factor in back to back division tiles in 2001-2002. He did well in the 2001 playoffs prior to the World Series, but overuse caught up to him in games four and five, and many fans will unfairly remember only that.  Kim came back in 2002 to pitch the best baseball of his career however. 

#3: Jose Valverde was a flamboyant closer with the nickname Papa Grande. His 47 saves in 2007 remain the franchise record

#4: J.J. Putz was a high efficiency closer that had a huge season in 2011 with 45 saves, and followed that up with 32 the next year. His time was shorter the others on this list but for two and a half years he was lights out when he was able to pitch. 

#5: Archie Bradley was a workhorse reliever who had many big moments for the team. While many will remember his stunning triple in the 2017 Wild Card game, the team doesn't sniff the playoffs without his dominating pitching in a setup role. 

Honorable mentions:  Matt Mantei, Brandon Lyon, and Andrew Chafin are among relievers that have all excelled for at least a portion of the time in Arizona. If one of your favorite relievers is missing from this article, check out the three  articles from 2022 chronicling the best single seasons of reliever in franchise history.