I think you will never know about injuries,I think the bottomline is how lucky you are.
I have played this game for 5 seasons,and I did have 3 injuries,2 players for 2 weeks and 1 for 3 weeks.
I did have many players injured for just 1 match,and the next game they could play again,maybe it has to do with your doc,try to buy a level 3 with speciality taping injuries,and than most of the time you will be OK..