The tennis players seem to take care of making sure they are fit enough for a 5set match(well some do)
Maybe the footballers don't take enough responsibility for the poor results. They can rely on other players or hide amoungst the team and the blame is often put on the managment and directors.
I guess in tennis if your not fit enough, it is only you thet suffers.
The footballers probably couldn't give a stuff that they are knocked out or the Euros. They can go back and play golf and getting drunk!
There clubs are probably very happy too, not having there players risking getting injured.