The confidence issue is a valid argument (although a good manager should be able to do something about that),
So far off the mark there, ridiculous assumption. Ancelotti, Di Matteo, Benitez, Mourinho, del Bosque....none of them are good managers then? Sure it might be part a manager's job to motivate etc, but confidence will come through good performances and goals, which comes through hard work and perseverance, which Torres seems to have lost..
but I'm not aware of any injuries he has had that have effected his physical attributes permanently.
He was constantly injured throughout 2008, 2009 and 2010, and came back from the World Cup injured...don't know how you can't remember any of that?
It doesn't have to be a serious injury to affect a player. Being injured means he won't train physically or mentally, so his ability/ quality will deteriorate, that's a fact. Look at Lucas- took him ages to regain any sense of form, same with Ramsey, Wilshere etc. Long term (either 1 bad injury or several less significant injuries) injuries will harm a players ability, you can't argue against that.