I think it is ok to be frustrated when players are out injured for extended periods.
I am frustrated with Dawes and Clark , I know they would be hating the injuries much more than me and did not get injured on purpose.
However when a player of their calibre and cost has trouble getting on the park it is very frustrating.
At this point ( end of 2013 )IMO the Dawes and Clark acquisitions are a failure.
2014 may well turn that around.