Watch him in his performances for us. He barely busts a gut anymore and plays like he either can't be bothered or he isn't fit (Which is worrying in itself and shows laziness) The Iheanacho goal for Leicester (whilst was a good finish) was all on Wanyama being on the wrong side of his man. He was also at fault for another goal, can't remember who's though. Mahrez maybe?
Then again, as stated in the second paragraph, it could be the extent of his injury that we're not 100% sure of. I think I read he has knee cartilage issues.