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It's been well over 600 days since Pro Bowl wide receiver Victor Cruz last played a regular-season NFL game. That time away, combined with the fact the New York Giants star is approaching 30, has had some wondering whether Cruz will ever recapture the salsa-level magic he possessed between 2011 and 2013.

Cruz suffered a horrible knee injury in 2014 before missing the entire 2015 season through a calf injury that he said came about as a result of overcompensation, per Jordan Raanan of NJ.com. Essentially, the belief is one major injury led to another major injury, limiting Cruz to just six starts for the 2014 season.

Cruz, however, produced hope via social media on Monday with an Instagram video that showed him running an explosive route before making a leaping catch. Sure, it was a small, controlled sample, but he looked a lot like Victor Cruz circa 2013.

Can Cruz make it all the way back this summer and fall? The truth is not even his doctors know for sure. Because while Cruz is a world-class athlete, and world-class athletes routinely make a habit of defying odds, the injury he suffered in 2014—a torn patellar tendon—typically gives athletes crapshoot-level odds at returning to form.

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Throw in the extended time off as a result of another soft-tissue injury—he had surgery in November to repair torn fascia in his left calf—and you have to wonder whether Cruz can get it all back.

A study published in June by the American Journal of Sports Medicine, cataloging postoperative outcomes of orthopaedic procedures in NFL players, found only 50 percent of players returned after having surgery on torn patellar tendons. That's particularly daunting considering that 79.4 percent of players returned to play after orthopaedic procedures in general, which makes patellar tendon repair an outlier.

Mai et al and the Northwestern Hsu Lab for Sports Outcomes (American Journal of Sports Medicine)

In fact, per that study, those recovering from patellar tendon surgery fared the worst "with respect to the return-to-play rate, career length after surgery, games played, and performance at one year and two-to-three years after surgery."

Not only are those who had patellar tendon surgery much less likely to return, but they also return for less time and perform at a lower level than those who have suffered other common musculoskeletal injuries such as torn ACLs or ruptured Achilles tendons.

Anecdotal evidence certainly supports that:

Center LeCharles Bentley tore his patellar tendon as a 26-year-old in 2006. Despite the fact he was coming off a Pro Bowl season, he never played again.

Running back Cadillac Williams suffered back-to-back patellar tendon injuries to separate knees in 2007 and 2008. The former 1,000-yard rusher battled back to start 24 games in 2009 and 2010, but he averaged just 3.8 yards per carry during that period. His career came to an end the next year.

Running back Ryan Williams suffered a torn patellar tendon as a rookie in 2011. The second-round pick returned for five games in 2012 but never played another snap after that. "Growing up I thought that the worst injury you could have is the ACL," Williams said last year, per Fox Sports. "Nah, when you tear that patellar tendon and your kneecap shifts to your thigh, that's something I wouldn't wish on my worst enemy."

Safety Jim Leonhard suffered the injury late in 2011. He had started 53 games in four seasons but started just 13 over the next three years before retiring.

Wide receiver Greg Childs tore both patellar tendons before his rookie season in 2012. He never played a regular-season game.

Wide receiver Brandon Gibson tore his patellar tendon midway through the 2013 season, returned to play 14 games with the Miami Dolphins in 2014 but hasn't played since.

Linebacker Jerod Mayo suffered the injury as a 28-year-old in 2014. He played sparingly in 2015 before announcing his retirement.

There are some positives, however:

Safety Nate Allen has never been a star, but he represents hope. The 2010 second-round pick suffered a torn patellar tendon late in his rookie season but missed only the first two games of the 2011 campaign and was a regular starter for each of the next four years with the Philadelphia Eagles.

Cornerback Patrick Robinson missed most of the 2013 season because of the same injury, but the former first-round pick has battled back to play 30 combined games the last two seasons with the New Orleans Saints and San Diego Chargers.

Cornerback Morris Claiborne missed most of the 2014 season through the same injury, but the former first-round pick battled back to start 11 games for the Dallas Cowboys in 2015.

A lot of regular people can go about their everyday lives with a torn ACL, which explains why the recovery—while also grueling—isn't completely debilitating. The same can't be said for a torn patellar tendon, which in all cases requires surgery and extended rest during the rehabilitation process.

"It needs a period of immobilization after surgery so the tendon can heal and not stretch out, which would lead to weakness," said Dr. Robert Marx, who is a professor of orthopedic surgery at Hospital for Special Surgery (HSS) and the Weill Medical College of Cornell University in New York. "So between the magnitude of the surgery and the resulting stiffness, that leads to atrophy and weakness. The recovery is very prolonged."

The additional problem with patellar tendon repair is it's not cut and dried. Instead, the procedure requires finesse. The goal is to restore proper tension in the tendon, but there's a risk of making it too tight or too loose.

"The tricky part is essentially how much tension you place on the sutures and which position the knee is in when you tie them," said Dr. David Geier, an orthopedic surgeon and sports medicine specialist based in Charleston, South Carolina. "The risk is if it's overly tight, you struggle to get range of motion back. If it's overly loose, you can't generate the same force. That's not to say it's impossible, but that's just one more element that makes the rehab tricky."

Further complicating things for Cruz is it appeared he had recovered from that initial patellar tendon repair last summer before suffering the calf injury at training camp. That injury, which his camp believes stemmed from the original knee injury as a result of overcompensation, didn't heal as expected, and Cruz was forced to undergo a procedure on the calf in the fall.

Victor Cruz: Major injury timeline Date Injury Age Result October 2010 Hamstring 23 Missed final 13 games December 2013 Knee 27 Missed final 2 games October 2014 Knee 27 Missed final 10 games August 2015 Calf 28 Missed entire season Pro Football Reference

When you're recovering from patellar tendon repair, the quad in the injured leg is particularly weak. That could in theory result in muscle asymmetry, which could cause an athlete to favor his stronger, seemingly less vulnerable leg. If that explains what happened to Cruz, it's the best-case scenario because it indicates he hasn't simply become prone to chronic soft-tissue injuries. And besides, there's no weak leg left for him to favor.

"Supposedly after you get it fixed it'll be 100 percent," Cruz said of the calf earlier this year, per Raanan. "It's a soft-tissue injury so it should heal pretty well on its own."

But there's no hard science on compensation injuries.

"It's one of those correlation-causation type of things," said Geier. "It's really hard to prove that one injury led to another. But we do know that with some injuries if you're weak on one side compared to the other, you're more likely to injure the other side. It can be in your head, it can be very subtle side-to-side differences in terms of strength. It could be tightness of the knee on one side versus the other. But it's hard to say for sure that any one factor caused this."

And thus, if the calf wasn't strictly injured as a result of overcompensation, Cruz could have a problem on his hands.

Dr. David McAllister, an orthopedic surgeon at the UCLA Medical Center with expertise in knee ligament injuries, noted these types of injuries usually hit athletes later in their careers "as a consequence of age as well as all the mileage athletes put on their bodies."

That might help explain why NFL players are statistically less likely to return to form after suffering torn patellar tendons compared to other soft-tissue injuries. And it also might indicate these injuries have hit Cruz because his body is breaking down earlier than many might have expected it to.

"Healthy tendons don't usually just snap on their own," said McAllister. "Usually it's a tendon that is starting to wear out. So another explanation possibly could be that this guy's whole body is starting to break down and that's manifested by multiple soft-tissue injuries in his body."

Marx, Geier and McAllister all expressed optimism that Cruz could indeed reemerge as a regular NFL starter. And considering the state of the Giants offense, as well as the need for experience and leadership inside that evolving locker room, that might be enough to help put Ben McAdoo's squad over the top.

Odell Beckham Jr. has already become a star, but he's 23 and can't carry the load. The only other receiver on the roster beyond the age of 26 is Dwayne Harris, who is better suited to being a special-teamer.

Cruz's mere presence would be highly appreciated. But there remain legitimate concerns regarding his ability to bounce back permanently from multiple soft-tissue injuries at his age, especially considering patellar tendon problems typically cost patients some of their speed and explosiveness.

This is a man who made his money on speed and explosiveness. Thus, even if he returns, Victor Cruz might never be the same.

All quotes were obtained firsthand unless otherwise indicated.

Brad Gagnon has covered the NFL for Bleacher Report since 2012.

Follow @Brad_Gagnon