Fantasy Basketball Draft Theory: Injured vs "Injury-Prone"

August 14, 2018

Trevor Crippen considers how to think about NBA players who are "injury-prone" vs. players who are already injured in fantasy basketball drafts in RotoBaller's series on Fantasy Hoops Draft Theory.

Right up through the end of the 2017-18 NBA draft season, fantasy owners were regularly taking Kawhi Leonard with a top 10 pick despite no assurances of when he'd return to the Spurs (his average ADP across ESPN, Yahoo, and CBS finished at 9.7, per FantasyPros). The thought process was that he had top 5 fantasy upside and a floor at around 10th overall if healthy. You just had to wait out this early injury and you'd score a superior pick. Unfortunately, that didn't work out too well, and owners greatly regretted taking him ahead of the likes of LeBron James, Nikola Jokic, and Chris Paul. Kawhi was hurt, and we just sort of ignored it.  It's not like he should've gone undrafted -- there's no way we could've predicted the series of events that followed -- but we didn't factor it into his value enough if we were still taking an injured Leonard over sure-fire elite contributors like James and Jokic who were perfectly healthy and primed to produce big numbers.

Meanwhile in Memphis, Tyreke Evans was finally healthy and lighting it up in the preseason. He was looking to be a big part of the Grizzlies rotation going forward with some upside. However, most owners ignored him as he went largely undrafted or as a final round selection in ESPN and Yahoo leagues. He was seen as so injury-prone that it was inevitable he'd just get hurt again, while his past performance in injured marred prior seasons masked how effective he could actually be in an injury-free season. Even after the Grizzlies suffered injuries to Mike Conley and Marc Gasol that thrust Evans into a central role in their offense, many of us faded him as a waiver pick up or immediately tried to "sell high" on him in a trade before he got hurt. The trouble is, we couldn't sell high, since we were all overrating the risk of him getting hurt and continuing to underrate his potential as a consistent fantasy producer until well into the season. Those who circumstance backed into owning ended up getting 54 top fifty caliber games out of Evans for essentially no cost.

These are the two sides of valuing injuries that I've consistently seen in the fantasy hoops game. We don't take injuries enough into account in valuing players if we see them as safe commodities who haven't burned us in the past, despite the fact that these injuries might hamper their production past the point where they return to the court.  See: Leonard or Isaiah Thomas. Meanwhile, we miss out on opportunities when it comes to "injury-prone" players who have burned us in the past. See: Evans or Derrick Favors. Adjusting a player's value for an injury or the likelihood of getting injured is very difficult, so it's worth stepping back and looking at this. Let's start off with some data, and then look for where some potential opportunities and risks exist in the 2018-19 NBA season.

Fantasy Basketball Draft Theory: Injured vs "Injury-Prone"

Do Games Missed in the Past Predict Games Missed in the Future?

It's always nice to get a good chunk of raw data to back up the theory. So I took a look at the list of the 125 players with the highest ADP across ESPN, Yahoo, and CBS last year -- a good sample of "universally drafted" guys -- and figured out how many games each played in 2016-17 vs how many they ended up playing in 2017-18.  Guys with 82 games played in one season were definitely going to play less in the other, while guys with 7 were definitely going to play more in the other, so I broke them into buckets of "mainly healthy" with 70+ games played and "missed time to injuries" with fewer than 70 games played.

It turns out there was a strong correlation between guys who played over 70 games one year with those who played over 70 the next -- 62.8% of the 86 universally drafted who played over 70 in 2017 also did so in 2018.  Meanwhile, only 33.3% of the 39 universally drafted players who played under 70 games in 2017 managed to hit 70 in 2018. Guys who missed games continued to miss games.

Of course, this is slightly conflated some guys who were recovering from major surgeries that predictably cost them time in both seasons -- Joel Embiid, Zach LaVine, Jabari Parker, Rudy Gay, and Danilo Gallinari, being prime examples. Start focusing only on guys who are fully recovered, and the predictive power of past injuries starts going way down.

Diamonds in the Injury Rough

Where it really got interesting for me in breaking down players into these buckets was when comparing the ADP of each player to his final per game rank (using Basketball Monster to approximate rank). Of the 125 universally drafted players last year, only 30 outperformed their ADP by a full round or more. Of those 30, almost half (13) were in the "injured" bucket of those played fewer than 70 games the year before. That's way more representation than you would expect if leaps in production compared to ADP were totally random. Remember, the "injured" bucket was only 39 players, while the healthy bucket was 86. If you picked someone in the injured bucket, you had a 1 in 3 chance of their per game production being a full round better than their ADP, while if you picked someone in the healthy bucket you only had a 1 in 5 chance.

Some of the biggest home runs in the mid rounds of last year's drafts -- Victor Oladipo, Jrue Holiday, Robert Covington, and Clint Capela -- were players in the "injured" bucket who married a leap in per game production with good health for the season. Is there a way to more successfully pick out steals in the mid-rounds of this year's draft by looking at guys who were injured the year before? There's a decent explanation for why this data might actually be meaningful. The theory is this: the same injuries that limited their playing time in the year before also limited their production on a nightly basis. If they are younger players, these injuries may have also set back their natural development.

Picking Out Next Year's Steals from the "Injured" Bucket

So who are the next draft steals to emerge from an injury season with full health and improved performance?

Joel Embiid remains the blue chip in this crowd, with his first fully healthy offseason allowing him to work on improving his game.

Devin Booker, who suffered through some injuries last year in trying to single-handledly carry the Suns, could come back in his age 22 season with better health and better support with another huge leap in performance.

Aaron Gordon started off very strong last year before suffering an injury, then a collapse in performance. Perhaps with health this year, he could start showing what he showed last Fall on a more consistent basis.

Lonzo Ball may seem to be in an awkward spot with LeBron James and Rajon Rondo suddenly horning their way in on his ball-handling duties, but he was quite impressive last year despite a slow start and some injuries, and a healthy season combined with natural progression at his age could make for a nice leap in performance. We'll just have to hope the situation allows that to translate into fantasy production.

Brandon Ingram's fit with LeBron is much more natural, meanwhile. He showed flashes of excellence last year while playing only 59 games. He's still not even 21. A season of full health with LeBron facilitating could lead to big things for young Ingram.

Malcolm Brogdon had his second season cut short by injury, but was showing signs of an emerging ability as a potentially elite three point shooter. We didn't get to see what he might've done in the second half of last year, and with a full season of health, the former surprise Rookie of the Year could see a breakout in 2018-19.

Can You Avoid the Next Kawhi?

There's no way to avoid the risk of injury to your early round picks altogether. You can be as careful as you can be, and still Gordon Hayward's leg might snap gruesomely. But the lesson from Kahwi Leonard and other injured players is this: don't take your chances. Don't assume a guy will come back from injury. He might ghost like Kawhi. Don't assume he'll be the same player even when he does come back. He might be a shell of himself like Isaiah Thomas. When you're spending an early round pick or even mid-round pick, stick to the guys you can see on the floor right then and there during the preseason playing at a high level. Even if their history hasn't always been the best. If they still end up getting hurt, that sucks. At least you didn't draft a guy who already had the injury that ends up sinking your fantasy season.

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