Do you have something against Sanchez? Why do you seem to dislike him so much?
I think the Eriksen's situation is different from Sanchez's. Eriksen is only 27 and is in his peak years and while it's not a good look on him, I believe his lack of motivation is due to the fact that he doesn't want to be at Spurs. With Sanchez, I think it's a case of his body just gave up on him after his endless exertions with club and country over the years. Over the last decade or so, I think he had less than 3 summer breaks. Otherwise, he played a lot for Barcelona and Arsenal and god knows how many tournaments with Chile. If anything, it's a surprise that he didn't break down sooner, especially when you consider his playing style on top of the lack of proper rest.