I think the non stop Cricket these guy's are playing is the main reason for these injuries. A flashback for 2013 IPL, champions trophy, T20 game ... Ashes, I may have missed a few games for sure. A human body has some limitations and playing a Test match is a big challenge and getting proper rest is necessary before an important series, specially a Test match..
I guess you don't a lot about Watson and how prone he is to injuries. He really shouldn't be bowling if his body can't handle it. He keeps getting injured time and time again because he fancies himself as an allrounder. He performed best and largely injury free when he played purely as an opener.
Playing and bowling in the IPL right after another injury, and just before the Ashes series? Mmmmm......