OK, two things.
1. Rob was actually pencilled in to play an U21 game the Monday after the Cardiff game. As soon as that team left he was told that no one else thought he was ready and he was pulled out of full training for two weeks to do further strengthening work on his knee. The hamstring injury could have been related to his recovery, but he has a history of hamstring injuries in both legs going back to his teens, this one was minor and he would have been back but for a completely unrelated personal issue.
2. The majority of Sebs recovery has been under the current team, how his schedule might have differed I don't know.
Personally I think that the previous team did a great job on the stamina and overall fitness of the players, Joe Williams and our overall ability to last 90+ minutes most of the time are testament to that.
I differ from @Davefevs view and clearly yours when it comes to players recovering from injury, there are obvious examples like the failed attempts to rush Naismith back, but there are other stories which I would be happy to share with you privately if you would like.