Basically, situations that aren't particularly 'critical', in which you are looking to weight up the importance of winning the ball v's the safety of the player(s) involved. You can easily conjure up a hypothetical situation or just use Ben Arfa's incident from yesterday. So, say winning 1-0 with 10 minutes to go and the ball is deep in the opponents half. Either way, there are going to be moments where winning the ball back isn't that important and player safety can take priority.
Of course, there is the mental side to consider, so Hatem lacked the confidence to make a tackle. But still, if Hatem is still pulling out of such challenges in 6 months time I wont be particularly concerned if he is performing in other areas as you would hope/expect.