See this thread: http://forum.topeleven.com/bugs-tech...-injuries.html .
Sometimes it is about the opponent using hard tackles, but sometimes it is about something else - like a sort of predefined number. For the second case, there is nothing much you can do as good management of players, squad rotation, good condition, opponent not using hard tackles and so on does not seem to prevent injuries for this one.
For sure, it is annoying and becomes really frustrating if the thing continues. This game has become a specialist in annoying people or causing frustration.