Driven by deep data sets, sophisticated technology, and collaboration between skilled statistical and scouting staffs, major-league teams have become increasingly adept at projecting player performance. In some respects, assembling a roster is the easy part of building a winning team. The hard part is making sure that roster remains intact. Speaking at Internet Week in New York earlier this year, Athletics General Manager Billy Beane stressed the importance of predicting and preventing injuries:

The biggest indicator now—for a sports team—of whether you’re going to be successful or not is whether or not you stay healthy. The health of baseball players, the health of football players, is going to be a better predictor of a team’s performance. And the guy who gets his arms around that is going to be the wealthiest man in the world.

It’s easy to see why Beane—who has spent the last 15 years trying to make the most of Oakland’s modest payrolls—would ascribe such importance to health. According to BP’s injury database, 20 teams have spent $10 million or more on injured players this season, led by the Red Sox at $49 million. As a group, major-league teams have spent over $3 billion on player payrolls this season, and almost 16 percent of that total—roughly $480 million—has gone to players who were unavailable due to injury. The percentage is even higher if you exclude players with major-league contracts who aren’t on 25-man rosters and released players still being paid by their former teams. That’s a lot of cash that could have gone to good use elsewhere.

Of course, the impact of injuries goes beyond the bottom line. It’s also felt on the field: when starters are injured, more playing time goes to less talented replacement players, and team performance suffers. But a team’s financial and on-field fates are intertwined. The more prospects a team loses to career-ending injuries, the more it has to pay for free agents to fill holes. The more time a team’s established starters miss, the more it has to spend on the players who take their places. And the less success a team has in the standings, the more its attendance will suffer, the smaller its season-ticket base will be, and the less revenue it can expect to receive from merchandise sales and broadcast contracts. The ramifications from those missed opportunities to make money are often felt far in the future. The less money a team takes in now, the less it can afford to pay players later, which can lead to even harder times ahead.

Until Beane’s “wealthiest man in the world” discovers the secret to preserving players, teams will have to accept that some seasons hinge on who stays healthy. This season is no exception. Here are a couple divisions that could have looked different had injuries not intervened.

AL East
Four AL teams rank among the top 10 in WARP lost due to injury, a number arrived at by determining each injured player’s average WARP per plate appearance from 2010-12 and multiplying by plate appearances missed this season. The Red Sox lead all of baseball with 8.3 WARP lost. More talented teams tend to have higher WARP lost totals, since their players tend to produce more when healthy, but Boston also ranks second in days missed due to injury and fourth in percentage of payroll lost.

Given the distance in the standings between the Red Sox and Rays, Boston’s injuries probably only partially explain their current fourth-place position. However, injuries could prove decisive for the teams toward the top of the division. The Yankees have lost roughly 6.6 WARP due to injuries to position players Brett Gardner, Alex Rodriguez, and Mark Teixeira, among others, as well as prominent pitchers CC Sabathia, Mariano Rivera, and Andy Pettitte—and that’s without counting the potential contributions of Michael Pineda, who suffered a season-ending injury in spring training and was never on the active roster. Had the Yankees enjoyed better health, they might have a larger lead over the Orioles than 1.5 games. Then again, the Yankees have by far the oldest team in baseball, so they may have been lucky not to have dealt with more injuries than they did.

The Orioles have lost just 2.7 WARP to injuries, compared to 5.4 for the third-place Rays. Evan Longoria’s injury, which robbed the Rays of an estimated 2.6 WARP, accounts for the difference between the two teams’ WARP lost totals. It also comes close to accounting for the difference between them in the standings: the Rays trail the O’s by just 3.5 games.

AL Central
The Tigers lead the White Sox by one game. They’ve also lost roughly 1.2 WARP less to injury. If the two teams are separated by a similar margin at the end of the season, a slightly better health record might deserve some credit for salvaging Detroit’s season. It would be ironic if the White Sox missed out on October because of injuries, since the White Sox have long excelled at keeping their players in uniform. Even this season, the Sox have lost just 8 percent of their payroll to injuries, the same percentage as last season and the fourth lowest in baseball. However, not counting Victor Martinez, who was never on the active roster and whose injury prompted the Prince Fielder signing, the Tigers have lost just 4 percent of their payroll to injury, the best figure in baseball. If Detroit’s season ends in disappointment, the team won’t be able to blame bad health.

In the other divisions, the leads are large enough to have held up had injuries affected every team equally.

Injuries aren’t always random: some teams do a better job of avoiding them, whether by managing potential health problems more effectively or by targeting players who are less likely to get hurt. And some teams do a better job of constructing rosters with greater redundancy, putting good players in a position to step up if the starters go down (as Todd Frazier has in Cincinnati this season). The WARP lost totals above don’t account for how a team filled its holes, only that it had them. Still, Beane’s quote hits home: once a season starts, few factors are as likely to affect where a team finishes and how much money it makes as how healthy it is compared to the competition.

Rob McQuown and Dan Turkenkopf provided research assistance for this story.

​A version of this story originally appeared on ESPN Insider Insider.

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Unconvincing. How much of the variance between the Pythagorean projection on Opening Day and the team's actual performance that year can be attributed to WARP lost due to injury?

This post being from an Orioles fan, shouldn't you factor in the WARP of the replacements? Manny Machado has clearly been better than those who he replaced, and one of those who he replaced, Mark Reynolds, has done much better - defensively, at least - since being moved to first base. Nate McClouth and Michael Gonzalez have also been upgrades.

Billy Beane knows a whole lot more about baseball than I do, but I wonder if, given time and the right followup question, he might have added that, since injuries are a predictable part of the game, the indicators of the success of a sports team might include not only how healthy the team stays, but also how well the team does in promoting from within or importing replacement talent (for example, Ichiro) as the need arises.

You also know a lot more about baseball than I do, but this piece strikes me as fodder for whiners, and we don't got no
whiners in Baltimore (not this year, anyway)
Yeah, I didn't mean to suggest that the AL East standings would definitely look different. As I wrote, "The WARP lost totals above don’t account for how a team filled its holes, only that it had them." You're absolutely right that you have to look at who replaced the injured players and how they did. And even then, it's impossible to say what would have happened in the alternate-history version of the season: maybe the teams involved would have made some other roster moves or acquisitions if their situations had been different.

Basically, I just wanted to talk a bit about the importance of injuries, the benefits of figuring out how to avoid them, and the idea that they theoretically could (and at times have) helped determine which teams make the playoffs.
I think it's a little misleading to use payroll lost as an indicator, especially vis a vis the Tigers. Andy Dirks missed two months, and Austin Jackson one month earlier in the year. Both guys are productive position players who make the league minimum. To a lesser extent, you can make the same case for Avila's injury. Doug Fister also makes the league minimum and is one of the team's more productive players.

They were also hurt somewhat by the fact that a lot of their injuries did come in the month of May and due to the cascade effect, they had to plumb the depths for Brad Eldred, Matt Young, and Bryan Holaday.
It's definitely misleading as the sole indicator of how healthy a team was. For that purpose, I think WARP lost or days/games missed work better.
It is unfortunate that the majority of articles printed will give examples from all of the AL East teams except for the Blue Jays. I would be curious to see how the Jays compare in this breakdown, but again, they are not referenced.
They weren't referenced because they weren't really relevant here--they're not in contention like the top three teams, and they haven't had as extreme a season for injuries as the Red Sox. Corey Dawkins will be doing a more in-depth wrap-up of team-by-team injuries after the season, but the Blue Jays rate ninth with 4.6 WARP lost.
K, thanks much Ben. I appreciate the info.
The metric is misleading though because it also matters how the injuries are distributed. If one team loses a different member of the strating staff for 20% of the season, with no overlap, you can get by with your top 6 starting pitchers (with #6 pitching for which ever starter is injured). If instead, like the Jays did, you have every member of your starting rotation injured at the same time, you are pitching your #10+ guy. Straight static WARP doesn't capture that stacking of injuries, especially to starting pitching.