My perception is that sports are not like other jobs -- it's their life's passion. I do think athletes are different in that way.
As for Matarrita, I don't think his problem is a lack of care. I think too much passion makes players do things they shouldn't. And I wonder if it's also coaching -- does Vieira want him doing one thing, while his CR coach wants him doing something else? And does that chnage the way he plays? I don't think it's a like-for-like comparison.
I'd be even more cynical, I think the Euro transfer hype has Mata seeing $$, and I think he's got people in his ear reminding him that people pay for goals and assists not defense. He plays like a guy whose ego far out weighs his current abilities.