Should Ryan Shazier's Hamstring Injuries Factor into His NFL Draft Stock?

Currently suffering from a hamstring injury, former Ohio State University linebacker Ryan Shazier doesn't exactly carry with him the flashiest of diagnoses heading into the NFL draft. After all, it's just a hammy.

Right?

Well, perhaps.

News of Shazier's injury first surfaced during the NFL Scouting Combine when, according to the Cleveland Plain Dealer's Doug Lesmerises, it prevented the linebacker from running the 40-yard dash.

Lesmerises notes that Shazier returned to run at Ohio State's pro day on March 7. He posted a blazing time of 4.36 or 4.37 seconds, but he pulled up afterward with an apparent re-injury:

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Ryan Shazier came up limping just after finishing his 40 at Ohio State's Pro Day on Friday, but only after doing what he needed to do. Shazier pulled his hamstring, after not running the 40 at the NFL Combine because of a tweaked hamstring.

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Unfortunately, when it comes to the NFL draft, even an injury as benign as a pulled hammy merits attention.

Just look at the evidence.

In 2012, Grant Freckleton and Tania Pizzari published a systematic review of medical literature in the British Journal of Sports Medicine in hopes of answering one question: What places athletes at risk of hamstring injuries?

To investigate, Freckleton and Pizzari compiled data from 34 different manuscripts, and a few major trends became apparent.

For one, numerous athlete-specific factors—such as body-mass index (BMI), height and running speed—did not appear to correlate with an increased risk of hamstring strains.

More importantly for Shazier, however, is the finding that a prior hamstring injury places an athlete at a 2.68-times higher risk of a future one.

It is important to keep in mind that systematic literature reviews do not focus on the case of an individual athlete—or even a group of athletes, for that matter. Rather, they analyze an average of averages.

Additionally, most medical publications carry at least some degree of statistical or procedural weakness. For instance, Freckleton and Pizzari highlight one important point within the paper itself:

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The tendency to assess the variables in isolation may further confound the picture, since important interactions between variables may be missed and the influence of some risk factors may be overstated. [...] 

The interaction between risk factors is likely important, since hamstring muscle strain-type injury is considered to be a multifactorial problem.

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In other words, the authors caution against interpreting one variable—in this case a prior injury—all on its own.

Nevertheless, a study conclusion achieving statistical significance is no small feat, and when a potential high-round draft pick is on the line—and possibly millions of dollars—everything gets placed under the microscope.

In fact, Dr. Matt Matava—president of the NFL Physicians Society—told this author that even fully healed injuries come into play when doctors are determining an athlete's medical grade.

"A player might have an injury that is completely healed with no lingering issues, but usually, if he has had a previous injury, his score is still slightly reduced," Matava explained.

According to Matt Miller—Bleacher Report's NFL draft lead writer—Shazier suffering two hamstring injuries in a short time period certainly doesn't help, either.

"As it stands now, Shazier's athleticism and burst make him a late-first-round talent," Miller affirmed. "That said, if his career is at higher risk of recurring hamstring injuries, teams will take notice. A draft-day fall for Shazier wouldn't be a surprise if NFL doctors are concerned."

Nothing yet suggests the former Buckeye will fall victim to a case of the hammies, but precedent in the NFL already exists.

For instance, Green Bay Packers wide receiver Jordy Nelson fell victim to the hamstring bug during the latter half of the 2012 season. Then, in 2013, Mike McCarthy's team placed cornerback Casey Heyward on injured reserve due to lingering hamstring troubles.

Running back Darren McFadden also comes to mind as a player who has suffered multiple hamstring injuries over the years—one in 2010 and two in 2013.

Hopefully, Shazier does not follow suit. Indeed, he may very well fully heal without incident—and perhaps probably will.

That said, the very first scent of trouble already exists.

It may not be an ACL. It may not even be a shoulder.

But it is worth considering.

Dr. Dave Siebert is a resident physician at the University of Washington who plans to pursue fellowship training in Primary Care (non-operative) Sports Medicine. Quotes were obtained firsthand unless otherwise noted.

Follow @DaveMSiebert