I was mostly joking.
But it could have something to do with the fact that there are different types of injuries.
If you have a torn ACL, you are done for the year. There may be other injuries where you can get beat on, and beat on and beat on and still remain functional, as long as you are within a certain threshold (kind of like the Terminator).
Hypothetically, you may not cross that threshold in year N, but the cumulative toll may have brought you close to it. Even with an offseason of rest, the cumulative toll administered by a "370 beating" may leave a RB, while still functional, in some intermediate state (i.e. - more fresh than the end of year N, but not as fresh as the beginning of year N). If so, they would be closer to crossing past the red line and the minimum needed to remain within the functional level threshold in season N + 1 than they were in season N. Might not happen week 1, 2, 3, etc. But at some point, 370 beating N + 1 RB could be more vulnerable to hitting a tipping point.
This outlook presupposes that some injuries may not be as simplistic in an inferential or detectable sense, in that they must have some strictly linear relationship between injury and performance (10 or 20% severe ankle sprain, whatever that means to quantify it, would necessarily lead to an exact 10-20% reduction in stats on a precise, one-to-one correspondence, lock step manner).
Not to mention, some players get shots to make it through the season. It is pretty easy to see how you could get through the season on powerful pain meds and adrenaline, but in a way that leaves you in a reduced state in year N + 1, relative to year N (it would be kind of surprising and counterintuitive if that WEREN'T the case, from that perspective).
Supposedly a true story. A drummer of a nameless band that was going to provide stadium entertainment (half time, before, after?) could barely walk, and was in excruciating, agonizing pain, possibly from a herniated disc in his back? A team doctor or player may have hooked him up (why a rock drummer would need to be hooked up with pain meds is a good question, so maybe this is an apocraphyl story, but I could absolutely see it taking place, for me, the details, not all of which I remember, at the time carried an air of genuineness, authenticity, verisimilitude) and he was jumping around, doing cartwheels and backflips, saying, this stuff is GREAT! Of course, the next day, he was far more hurting than he was in the first place. Pain is nature and our bodies way of telling us to take it easy so as to not damage the bio-organism any further, and give it a chance to rest and recuperate, allowing natural healing mechanisms to do their work. Overriding our natural, internal warning systems to shut it down, with pain pills can allow one to muddle through some games in a current season, but by masking symptoms of potentially serious damage, could be courting disaster and have severe reprecussions down the road, like as soon as the following season?
Perhaps Murray can be one of the outliers, but the pattern is as clear as day.
