How much did injuries hurt the 2016 Arizona Diamondbacks?

When A.J. Pollock broke (or rather, rebroke) his elbow in the penultimate game before Opening Day, the Diamondbacks had lost an All-Star, and were left to play catch-up as a result. Their Opening Day center fielder, Chris Owings, had played there for the first time in his professional career, during the final warm-up contest. It seemed to set the tone for the 2016 season. But can we put a figure on how much they absence, not just of Pollock, but David Peralta, Zack Greinke, and others, cost the team?

The DL crew

Here are details of all the DL stints for the Diamondbacks in 2016. I’m not going down to the “day to day” nicks and bumps. For each, we have the player, DL type, injury, start date, retro date (if appropriate), end date (if appropriate), and the team’s record during their absence.

How does that compare?

That’s 11 different players - poor Peralta ended up going on the DL three different times! - and a total of 665 games lost. That seems a lot, the equivalent of losing more than four players for the entire season. But perhaps it’s not. For if we look at other teams, we get a different picture. We can find this out from the Baseball Heat Maps data, It uses days rather than games, and tells us the Diamondbacks lost a total of 831 days. [As an aside, I have serious doubts about the accuracy of the Spotrac DL tracker, which says, for instance that Chris Owings lost 198 days to injury... while appearing in 119 games]

It would actually be close to the fewest days lost of any NL West team, 31 more than the Giants (800). Far, far ahead of this pair are both Colorado (1,498 days) and San Diego (1,568). However, it will come as no surprise that far and away the champions were the Los Angeles Dodgers. They lost more than an entire roster of players to the DL at one point or another: 33 stints by 27 different players, who missed a total of 2,418 man-days in 2016, close to three times the amount of the Diamondbacks. That they still won the NL West is something of a good counter-argument to those who blame the D-backs’ injuries for their failure. However, it has to be pointed out that a $250 million payroll doesn’t exactly hurt, in terms of buying depth and flexibility.

What was the impact?

Not all DL stints are equal, obviously, and not even all days missed are equal. Pollock missing time hurt the Diamondbacks more than Herrmann. If we’re to look at the impact of injuries, we need to figure out what the players worth “would” have been. To do that, I’ve taken two different approaches. For players who missed less than half a season, I’ve pro-rated their 2016 bWAR for the missed time. You miss 1/6 of the season, for example, the cost was 20% of your actual 2016 bWAR (since you played 5/6 of the year). However, the closer the number of games played tends to zero, the more volatile bWAR. So for those who missed more than half a season, I’ve used 2015 bWAR as the standard. Fortunately, the three players affected (Pollock, Peralta and De La Rosa) all played full seasons in 2015, giving us a solid baseline.

The table below shows the results. For each player you get the number of games missed, the “base value” [either 2015 or 2016 bWAR, as explained above] and the number of games over that was achieved. The final column is the projected amount of bWAR lost, pro-rating the base value per game, over the time missed.

There are a couple of assumptions built into the total, which projects that a completely healthy Diamondbacks team would still have been below .500, at around 79-83. Firstly, there has never been any completely healthy baseball team. All teams will have injuries over the course of the season, and these need to be handled. It’s utterly unrealistic to claim otherwise. Secondly, it presumes the players who come in truly perform at replacement level, which may or may not be the case. Matt Koch, for example, was worth 0.9 bWAR, good enough for fifth-best on the 2016 D-backs. A fully healthy team likely wouldn’t have benefited from that.

Comparison to previous years

Makakilo reminded me I’d done this exercise before, looking at how much the team lost to injury in 2014 and 2015. That method did include a slight tweak, capping the value lost at a minimum of zero, on the presumption a team can’t get “better” purely through a player being injured [though as noted above, their replacement can certainly help]. That applied to the 2016 contributions from Socrates Brito, Andrew Chafin and Shelby Miller, all below replacement level overall, and meant the total amount lost this year to injury ticked up slightly, to 10.1 wins. That falls somewhere between the 2014 and 2015 “hospital bills” in Arizona, which were 13.7 wins and 4.2 wins respectively.

The three-year average for the D-backs now sits at 9.3 wins lost to injury. If that’s indeed the case (though it would likely take a bigger sample size, of both years and teams, to establish with greater confidence if it is), then this year really wasn’t very far off the mark in terms of what should be expected. Arizona may have been hurt in particular by the loss of Pollock and Peralta (together responsible for more than eight of the ten wins), but at 831, the total days lost this season was 60 fewer than in 2015, and 553 fewer than in 2014. So it appears the D-backs were actually luckier than of late, in terms of the number of injuries suffered by the team and their severity, if not necessarily their overall impact.