Throughout the offseason, Seattle Seahawks head coach Pete Carroll has expressed optimism that tight end Jimmy Graham will be able to return and contribute to the offense in 2016.

Graham sustained a ruptured patellar tendon in a Nov. 29 game against the Pittsburgh Steelers. He did some light jogging and caught passes from Russell Wilson before practices during the spring. Carroll said that the team won't rush Graham during training camp, but he expects the tight end to be ready for Week 1 of the regular season, barring unforeseeable issues.

By all accounts, Graham is doing everything in his power to get back on the field, but there's no downplaying the seriousness of his injury.

During a recent podcast, ESPN injury analyst Stephania Bell explained why it's so difficult to come back from patellar tendon ruptures.

"It's this big tendon that anchors your quad, that large muscle in the front of your thigh, to your shin," she said. "So when it ruptures, essentially you incapacitate your quad. That's why guys go down in a heap when the injury happens."

New York Giants wide receiver Victor Cruz suffered a ruptured patellar tendon in 2014. Last season, he was sidelined by a calf injury, but Bell noted that the issues could have been connected.

"If you look at what Victor Cruz said later in the season, he said, 'I believe that calf injury came from me compensating always having that leg -- because it was on the opposite side -- had to do all the work while I was recovering from the patellar tendon injury,'" Bell said.

There are two questions with Graham. One is: When will he return to the field? And the second is: What will he look like when he does come back?

Bell said the biggest issue athletes have after this specific injury is regaining their strength and explosiveness. Even if they are able to get back to where they were, it often doesn't happen in the first year back.

"A study just published in June of this year in the American Journal of Sports Medicine looked at orthopedic procedures on over 550 NFL athletes," Bell said. "And of all the different surgeries that these guys have, those who fared the worst when it comes to rate of return to play and performance metrics like yards gained and touchdowns scored, [it was] patellar tendon repair.

"And their careers were shortened overall significantly. It's not to say that one individual can't come back and be phenomenal, but it's telling you that the odds are against them in terms of returning to form."

The Seahawks are committed to giving Graham every opportunity to come back and be a difference-maker. There doesn't appear to be any scenario where he'll be left off the roster in 2016.

But Graham's contract carries a cap hit of $10 million in 2017. In other words, the Seahawks will have a decision to make depending on how he looks this year. History is not on Graham's side, but he'll try to do everything in his power to be the exception when it comes to athletes returning from patellar tendon injuries.