Is this the worst Diamondbacks bullpen ever?

A week ago, we looked at whether this was the worst-hitting Diamondbacks’ team of all time. and concluded it should certainly be in the discussion. Things haven’t exactly improved there since, the team batting .209 with a .630 OPS over the past week. But it’s not the only area of the team whose level of suckage has reached near-epic levels in terms of Arizona history. While the D-backs’ bullpen has, remarkably, posted a winning record this year, going 11-9, most of those wins (six) came in contests where the Arizona starter did not complete five innings, and so we ineligible for the W. It then becomes the official’s scorer’s choice as to which reliever gets it instead.

[As an aside, starter wins overall are down. This year, even with the designated hitter meaning NL pitchers no longer get pinch-hit for, the starting pitcher has got the W barely a quarter of the time, 25.4%. Last year, the same figure was 29.8%. The average starter is no longer going five frames, with the mean outing now being just 4.8 innings and 80 pitches]

Looking past the W-L record shows a rather more troubling picture. The ERA has been 4.94; not good, but well below the worst figure in team history. That would belong to the 2010 bullpen, who had an ugly 5.74 ERA. Just this year, there are currently seven teams in the majors with higher relief ERAs. Heck, four teams are north of six. But there are two areas where Arizona’s bullpen have been particularly bad, and have indeed set new franchise marks. Let’s take a look at each of those in more detail, and pin down who have been the worst offenders.

Walks: 5.18 per nine IP

We’ve seen all along the problems the 2020 pitching staff has had with walks. They’ve already had seven games with eight or more BBs - that’s more than all of last year, over a full 162-game season. That’s not all on the relievers, with the Diamondbacks’ starters also at an all-time record walk rate. However, they are down below four (3.94). Only twice previously had the Arizona bullpen reached a walk-rate as high as 4.4 per nine innings. The record had been 5.07, set by the 2004 Diamondbacks, and any time you break a mark set by that team is never a GOOD thing...

Some of it is due to reliever churn, leading to the team having to go further down the depth chart. Through 48 games this year, Arizona have used 18 relief arms, not including Carson Kelly. The D-backs have basically run through two complete bullpens and then some, in barely seven weeks. It’s half as many again as the dozen used through 48 games last year (again, not including emergency catchers). Hence, we find the names of Matt Grace, Joe Mantiply, Travis Bergen and Joel Payamps - with all respect, players we probably would not have wanted to see pitch with the Diamondbacks this year - combining for fifteen walks over just ten innings of work.

But it’s not all that. Of the seven most-used relievers by innings pitched, three have walk rates that are above that record-setting average. Taylor Clarke is at 5.28; Junior Guerra is at 5.85; and Kevin Ginkel leads the pack, with 13 walks in 16 innings, a rate of 7.31. That lack of control is undeniably a large factor in why he was optioned off the roster last week. It’s odd, because last year, Ginkel’s walk rate was less than half that, at 3.3. The same, to a lesser extent, goes for Guerra (3.9) and Clarke (3.2). Walks by relievers across the majors are up this year, but only from a rate of 3.75 to 4.02, so certainly cannot be blamed for all of the increase.

Home-runs: 1.38 HR per nine IP

This is eleven ticks about the previous worst figure of 1.27, set in 2010. This is an area where the MLB-wide trend has actually gone the other direction, with reliever HR rate down on last year, also by eleven points. And here, the situation is even more pronounced, and can’t be blamed on the replacement-level arms. More than half of the relievers with 15 IP (five of eight), have a home-run rate of 1.69 or higher. Leading the parade of shame is Hector Rondon, who has allowed five home-runs over his sixteen innings, a 2.81 rate. The team rate would be considerably higher, if it wasn’t for Stefan Crichton, who has allowed one long-ball over his 21.2 innings.

xFIP: 5.06

ERA, as a number, is imperfect for measuring pitcher performance because it is significantly affected by the defense behind them, over which they have no control. Hence, a metric like FIP exists, which takes into account only the things a pitcher has control over, excluding all balls in play: so, strikeouts, walks and home-runs. By that number, the D-backs come in at 5.02, which is second-worst in franchise history, and not far below the worst, that belonging to 2010, who had a FIP of 5.09. Those who have been lucky - an ERA furthest below their FIP - include Clarke and Alex Young, while the unluckiest have been Ginkel and Rondon.

But there’s one step further we can go. xFIP is FIP, except with an estimate of how many home-runs they “should” have allowed, based on a league average home-run per fly-ball rate. That pushes the Diamondbacks’ figure even higher. While we can only work out xFIP back to 2002, Arizona’s figure this year comes in above five for the first time. At 5.06, it shatters the previous worst xFIP of 4.78 in 2004. I refer you to my previous comments about breaking records set by that incarnation.

There should, overall, be a bit of caution here. In total, the Arizona bullpen has thrown 182.1 innings, so only about one season’s worth for a regular starter. And we all know how their numbers can vary from year to year. The sample-size on home-run rate, for example, is well short of the point at which it should be expected to stabilize (1,320 batters; so far, the Arizona bullpen has seen 819). But with Arizona’s relievers as a whole below replacement level (-0.1 fWAR), and with long-standing names like Archie Bradley and Andrew Chafin no longer about, building a better bullpen is looking likely to one of the top priority tasks for Mike Hazen and his team this winter.