The impact of injuries on the 2021 Diamondbacks

Certainly, one of the narratives of the 2021 season for the Diamondbacks has been injuries. Over sixty games into the schedule and the team has not once been able to put out their best eight position players. In April, it was the position players who were dropping like flies. But as the calendar moved through May, and those got healthy, the pitching began to fall apart. Currently, four-fifths of the expected starting rotation - Madison Bumgarner, Zac Gallen, Luke Weaver and Taylor Widener - are all on the injured list. But what kind of impact has that had on the team overall? And how does that compare with how other teams have fared?

The injury table of woe

Below, you’ll find an grid which shows the team’s eight “best” position players and their five starting pitchers, for each of the 63 games played so far. A black box indicates a player was officially listed on the injured list for that game. You might want to get your scrolling thumb warmed up, and I’ll see you on the other side...

You can see the problems the team has had, and the above doesn’t even mention the bullpen (where we’ve lost Tyler Clippard, Joakim Soria, Chris Devenski and J.B. Bukauskas, for some or all of the season), or the bench - for our replacement players have had health issues of their own. It has been brutal

How do the D-backs injury issues compare?

It’s certainly the case that it has been a massive problem across all of baseball this year. Injuries are up by a severely troubling amount. Last week, USA Today reported:

• Through May, there were 104 soft tissue injuries that resulted in stints on the IL, a 160% increase over the 48 after two months in 2019.
• Hamstrings are going haywire – already the most common injury in baseball, they are up 193% since 2019, with 47 IL stints compared to 16 through May 2021.
• Adductors are in disarray – there have been 16 groin-related IL trips, compared to two in 2019’s first two months.
• And oblique strains and tears are up 83% - from 12 after two months of 2019 to 22 in 2021.

It’s generally believed the bizarre nature of last year’s campaign - spring training, stop, another batch of training, two month regular season - is the most likely culprit. Regardless, many other teams have also had their share of injuries, and some have been considerably more badly impacted than the Diamondbacks. However, exactly where Arizona sits, all depends on how you measure that impact. By days missed due to injury, Arizona currently sits at a total of 465. That’s actually the second fewest in the division, ahead only of the Rockies (415). It’s behind the Giants (645) and Dodgers (662) and barely half as much as the cursed Padres, who have lost a staggering 926 days already, most in the majors.

But not every day missed is equal. The loss of Ketel Marte hurts Arizona more than that of Clippard. Baseball Prospectus attempts to address this by working out how much value a team has lost, based on their player projections. Of course, those are always the subject of much argument, but it is at least a starting point. By this measure, the Diamondbacks have lost 3.18 WARP (Wins Above Replacement Player) to injury. That moves them ahead of the Giants (2.34), as well as the Rockies (0.85), but they still trail both the Padres (3.45) and the Dodgers (4.56). By this metric, the Mets are the most unhealthy team in the majors, having lost 5.40 WARP to the trainer’s table.

But if you look at the amount of WARP surrendered, as a percentage of the expected total, the Diamondbacks shoot up the table. They have lost 10.8% of their WARP, the most in the division. well ahead of the Dodgers at 8.6%. Indeed, the only team in the National League to have been cost a larger percentage of expected WARP are those Mets, at 12.3%. But these are all based off projections, not actual figures. Can we take a look at what the Diamondbacks have actually done, and use that to figure out where a 100% healthy team might sit at this point?

Your 100% healthy Diamondbacks

No baseball team has ever been 100% healthy, let’s be clear. So this is very much going to come up with a high-water mark of where the team “could” be. To reach a figure, I have only been concerned with the thirteen players on the table above. This figures that the team’s relievers and bench players are largely fungible, with an infinite supply of alternatives that could provide roughly equal value. So, for the eight position players, I have taken the bWAR they have actually produced in 2021, and pro-rated that, based on the number of games played, to get their value if thay had appeared in all 63 games. For starting pitchers, it’s pro-rated to 12.6 games.

Again, this is never going to be practical. Even a fully healthy Carson Kelly would not have appeared 63 times for the team. But it should give us an upper-bound on the cost of the team’s poor health this year. Here are the results for the 13 players:

Unsurprisingly, it’s the loss of Zac Gallen which has been most costly, a little short of one win. But probably more surprisingly, it’s Asdrubal Cabrera who has been the next most badly-missed D-back. This is largely due to the hot tear he went on at the start of the season. He was batting .289, which is a very good figure in this pitching heavy season, with an .866 OPS at the time he went on the injured list. But overall, this analysis comes out at a total cost of just 4¹⁄₂ wins lost to the Diamondbacks through injury. Given this is an “upper bound” approach, that’s not so far off the Baseball Prospectus figure of 3.2 wins. Sad to say it, even a fully healthy Arizona team would probably still be last in the NL West.

Footnote. Jack also sent over some notes to me, concentrating on the pitching side of things. It was very interesting stuff, but I’ve run out of time, since I want to get this up while the numbers are still accurate! Perhaps he’ll do his own analysis at some point...