It's not an assumption it's a fact. Its the reason why teams are so secretive with injury info in the days leading up to games. Their waiting to see how players feel before they scratch them. Guys want to play and they are willing to at the very least forfeit years of quality living after they retire to do so. Hell, You JUST watched the ENTIRE Seahawk secondary play throughout the playoffs and SB with injuries that more often than not are fixed with surgery where most docs would've recommended they not try to play with; Earl Thomas with a torn labrum, Chancellor a torn meniscus and Sherman with torn ligaments in his elbow....I'm sure their team docs recommended that they not try to play with those injuries and warned them of all the risks of potentially worsening their situation. And surely no orthopededic surgeon would be on board with a guy going out & playing a viscious contact sport like football with a bum shoulder. At the end of the day though, they were all out there playing weren't they? Are you viewing the Seahawks team docs the same way?
I just don't see how you can sit and watch these guys every sunday go out there with all kinds of knee, arm and shoulder braces on their bodies and think that team doctors have very much say in whether these guys get back on the field or not. & when you sit back & look at guys like RG3, Phillip Rivers & Jerry Rice's situation years ago, you can't possibly still believe what you wrote. I mean, ok yes, when these guys have grotesque Joe theisman-like injuries to where they clearly are unable to perform and/or are putting themselves in danger by going back out there, team docs step in, but at the point its pretty for everyone. Most all other injuries and stuff though, its mostly the player and coach. Now, that's not to say that the player will in fact get back on the field, but ultimately it is up to them.
As far as JD, If he's got any kind of love for the game & professional pride, he's chomping at the bit to get back out there. He'll likely downplay the amount of pain, tightness (to a point) and lack of confidence he may have in his knee to do that as wel