DUR does affect the time it takes to recover, but it also plays with the Health rating after an injury occurs.
A guy with a 90 DUR rating may only dip to a 70 Health if he suffers an injury. I'm pretty sure that same injury for a guy with a 20 DUR, will dip to a lower starting point. I'm pretty sure I've never seen a 90 DUR dip to 20 Health.
But similar injuries are not the same. I had a couple ACL a few weeks apart.
My guy with a 37 DUR dropped to Health of 26. Health, improving only 4 points per practice, that took 9 practices to reach a 60 Health, and 19 practices to get back to 100. With the no ratings gains while health is under 60, and limited until 100, his total rating changed 0 points for the year. Started 734. Ended 734.
Another player with an ACL had DUR of 21. He dropped to 46. Improving again at the slow 4 points per day, he was up to 60 Health in 4 practices. To 100 by 14 practices.
My suggestion has always been make the DUR a bit more important. Even have more injuries, but with quicker recovery for most. But all injuries have the same seriousness. Doesn't matter ACL or twisted ankle.
Have the injured guy's Health fall to the DUR rating after an injury. Then improve by that amount every practice.
If DUR is 30, if injured his health falls to 30. Means he won't play the next game. The next day Health is up to 60, probably still not playing. But up to 90 after two off days. 100 after three days.
If DUR was 80, an injury drops the health to 80. Meaning he could probably play immediately. After one off day that Health is back to 100.