Study shows Kobe likely to be on decline in 2013-14

Kobe Bryant may seem superhuman, but science is one opponent he may not be able to conquer.

Sometimes, science has to enter the equation.

It's lovely that Kobe Bryant appears to be superhuman at times. It's wonderful that he's too competitive to function like a normal human. It's great that he's still not ruling out returning on opening night, Oct. 29, from the fully ruptured Achilles tendon he suffered on April 12.

But up until now, the conversation has been too much the stuff of hopeful prognostications. Social media posts and interviews with Jimmy Kimmel do not a credible conversation make. Of course every player is different, and this is Kobe Bryant, after all, but he's just another person, just another glommed-together structure of muscle and tendon and bone. Science really does apply.

Lucky for us, the American Journal of Sports Medicine published a study in its August edition, titled "Performance Outcomes After Repair of Complete Achilles Tendon Ruptures in National Basketball Association Players." The study's authors – Nirav H. Amin, MD, Andrew B. Old, MD, Loni P. Tabb, PhD, Rohit Garg, MD, Nader Toossi, MD and Douglas L. Cerynik, MD, MBA – conducted their research before Bryant's injury, but the article was only just recently released in its entirety, and its contents offer clues as to what the aging Lakers guard may be in for.

The study looks at 18 players who completely ruptured their Achilles tendons and underwent surgical repair – just as Bryant did – between 1988 and 2011. The study does not publish the list of players it looked at, and though Deadspin put out a list of the 18, it is questionable for two reasons: (1) several of the players on it who in 2011 had gone on to play just one year and were designated as such have now gone on to play multiple years and (2) one player on the Deadspin list simply does not exist. (Neither Deadspin nor the doctors who authored the study responded to my requests for further information.)

For those reasons, I won't attempt to reproduce the list. However, noteworthy players who completely ruptured their Achilles tendons during that time include Elton Brand (still playing), Dominique Wilkins (continued to play at a high level), Isiah Thomas (retired) and Christian Laettner (continued to play).

And now, because medical research is hardly the most palatable reading for most sports fans, here a few of the key facts and findings from the study:

- At the time of injury, players' average age was 29.7, average BMI was 25.6 and average playing experience was 7.6 years. Thus, Bryant is older, more experienced and has a lower BMI than the average player in the study.
- That average age of 29.7 is about two years older than the average age of players in the league, and the players who were forced to retire as a result of the injury were on average older than those who returned.
- Certain factors increase the risk of Achilles tendon ruptures: older age, biomechanics, anatomic variations and changes in the frequency and intensity of play.
- Players who returned after their injuries missed an average of 55.9 games. They also showed significant decreases in their contributions (PER) and playing time upon returning.
- The study compared the injured players against a control group. Players in the control group matched returning players' positions, seasons played and statistics but had no history of significant surgeries. All of the returning players showed a worse decline after the injury than did the control group players in the corresponding years.
- The only predictive factor about whether a player would be able to return after surgery was his PER. For every increase in PER by one unit, a player's odds of returning to play increased by 18 percent.

Several facets of the study are especially interesting when applied to Bryant's case:

The demographics: At the time of Bryant's injury, he was 34-years-old, had a BMI of 23.7, was 198 cm. tall (the study measures players in centimeters), had played 17 seasons in the NBA, had a PER of 23.9 two seasons before and had averaged 33.9 minutes per game two seasons before.

His age, height and years of experience all trend toward the average numbers for players who did not return. His minutes played and PER two seasons before, however, are much more in line with the numbers for players who returned for two or more seasons; those players have tended to have played bigger minutes and had higher PERs two seasons before the injury. (His BMI is insignificant, in this case.)

What this means is that the factors Bryant has more control over – the playing time he's earned and his actual performance – dictate he should make it back for significant time. However, the factors over which he has little control, his age, experience and height, suggest a less optimistic outcome.

Risk factors: Two of the risk factors listed in the study especially apply to Bryant: age and a change in the frequency/intensity of play. Bryant will be 35 at the start of the NBA season, and though he's not old by conventional measures, he has played more minutes than any other active player in the NBA. Also, unlike most aging players, his playing time actually increased over the past two seasons; he went from averaging 33.9 minutes in 2010-11 to 38.5 in 2011-12 and 38.6 in 2012-13. Blame can't fall squarely on Mike D'Antoni – he was only Bryant's coach for one of the past two seasons – but there's certainly something of note there.

PER: The PER notes in the study are especially interesting, not only because by using the control group it mitigates the effects of the fact that PER naturally declines as a player ages. Beyond that, though, the note about past PER dictating future success in coming back from an Achilles rupture is particularly interesting. Bryant's 23.7 PER in 2010-11 was good for fifth-best in the NBA, and it means that he would have a full 18 percent better chance of coming back than Amare Stoudemire, were he to have torn his tendon at the same time. (Stoudemire's PER in 2010-11 was 22.7.) That's a large percentage that's working in Bryant's favor, especially compared to many of the players who've recently torn their Achilles tendons, and it gives some merit to the argument that Bryant will return simply because he is elite. The problem, of course, is that this is only accounting for returning, rather than for returning at a high level.

So what does all this mean? The study's conclusion reads as follows: "The NBA players who returned to play after repair of complete Achilles tendon ruptures showed a significant decrease in playing time and performance. Thirty-nine percent of players never returned to play.: Assuming Bryant will be a part of the other 61 percent of players who do actually return after the injury – it's hard to see how he won't – the first part of the statement is more relevant. Sure, maybe he won't see the drop-offs that some other players have, but decline is going to be hard to fight. Even Wilkins, who earned two All-Star berths as well as one All-NBA Second Team recognition after his Achilles rupture, was two years younger than Bryant at the time of his injury. Combine that with the fact that he'd played 9.5 seasons at the time to Bryant's 17, and the picture is if not grim, then tempered.

It will be no surprise if Bryant comes back quickly and competently from his Achilles tear. His followers – and even his detractors – should expect nothing less. However, he's still human, and this study simply puts numbers to what common sense could have told us all: the Kobe Bryant who takes the court this fall or winter will not be the player he was a year ago.

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