I am not sure if Hard Tackling is the cause of injuries. Any tackle would get the player injured if his condition is not ideal in the first place. That and random injuries just for the sake of giving managers a hard time. Playing at 90% condition and getting injured usually just gets the player out for 2-3 days.

From my experience playing against hard-tacklers, I've only gotten my player injured only 10% of the time. The odd thing is when I play hard tackle, my player seems to be the one getting injured. Anyway, it's not enough to justify that hard tackling causes injuries to opponents.

Or I might have been just lucky all these while....