5 Greatest Diamondbacks Left Hand Relievers
Relief pitchers are very difficult to evaluate. Their roles are often interchangeable, their sample sizes are small, and they often come in with runners on base or have varying degrees of leverage challenges.
As part of our series on best individual seasons by a Diamondback, here are the best five seasons by a left handed reliever in franchise history.
Number 5: T.J. McFarland, 2018
T.J. McFarland had the lowest ERA of any left handed reliever to work 40 or more games in franchise history. Moreover, he was a bullpen saver for Torey Lovullo in 2018. He worked four or more innings four times, and recorded four or more outs 21 times and his 72 relief innings were the most on the team. Left hand batters couldn't touch him, as they batted just .165 with a .388 OPS
McFarland's sinker induced ground balls 68% of the times, the third highest rate in MLB in 2018. The only thing keeping McFarland from ranking higher on this list was he was not used in many high leverage situations until late in the year. Many of his outings in the first half came with the team behind, but that changed as the season wore on and his excellence demanded more of a leverage role.
Number 4: Joe Mantiply, 2022
Joe Mantiply was the Diamondbacks lone representative at the 2022 All Star Game. He had an unbelievable first half with a 2.22 ERA and walking just three batters in 38 innings. Nobody was used in more high leverage situations throughout the year than Mantiply. His average leverage index, or aLI was 1.51. A leverage index of 1.0 is "normal" pressure, and an aLI of 1.51 means the pressure he faced was over 50% higher than a normal reliever.
That started to catch up to him perhaps over the second half of the season as his ERA was over a run higher after the break. But it was still a very successful season for Mantiply and he will always have the All Star label next to his name.
Number 3: Jorge De La Rosa, 2017
At first blush Jorge De La Rosa may seem to be out of place here with a 4.21 ERA. That was still better than average however, (112 ERA+) as 2017 was a very high scoring year. But what set De La Rosa apart was his incredible work with inherited runners. He inherited 33 runners through the course of the season and just one of them scored, or 3%. (MLB average IRS% is 30%)
This led to one of the highest WPA (Win percentage added) by a left hand reliever in franchise history. Simply put, when tasked with putting out a fire with men on base he virtually never allowed a run. On a team that went to the playoffs, that "clutch" value was well behind his ERA rank.
Number 2: Andrew Chafin, 2015
In 2015 Andrew Chafin had his best season as a Diamondback. Leading the team in relief innings pitched, he was second on the team among all pitchers in ERA and WAR, including starters.
It was his first year as a reliever, having been a starter throughout his minor league career and in his cup of coffee in 2014. Chafin had a .185 BA against vs. left-hand batters, but was almost equally as tough against right-hand batters, limiting them to a .222 BA. His 16 holds were second on the team to Daniel Hudson.
Number 1: Greg Swindell, 1999
The best season by a Diamondback left hand reliever came in the organization's second season. Greg Swindell ranks first in WAR and 2nd in ERA by a lefty reliever. (min. 40 IP) For the year he allowed just 9 of 37 inherited runners to score, (24%).
But most importantly his 2.6 WPA (Win Percentage Added) is far and away the best of any lefty reliever ever to toe the rubber for the D-backs.
Time and again he he got outs when it mattered most, especially after the all star break and down the stretch. From July 16th onwards he had just a .132 ERA in 34 innings as the D-backs charged down the stretch towards 100 wins and a division title. Swindell also had three scoreless outings in the 1999 divisional playoff series against the Mets
Honorable Mention:
Kyle Nelson posted a minuscule 2.19 ERA ERA in 37 innings of work in 2022. Several injuries kept him from appearing in more games, but he was excellent when able to post up. Torey Lovullo started going to him in more high leverage situations as he earned trust.
