#4 The player's age
Ronaldo recently stated that although he is 33, he feels biologically 23. Blessed with incredible fitness and a Greek-god like physique that his juniors would envy, he has a point. Yet, those comments were slightly exaggerated.
Ronaldo's role has reduced in recent seasons. He is no longer a winger, but more of a penalty box poacher.
While he is extremely effective in that role with 44 goals this season, his overall contribution has gradually reduced. Against Liverpool, he had the fewest touches among the Madrid players to complete 90 mins. This season is also the first time 'CR7' has failed to muster over 10 assists since joining Real.
United youngsters Anthony Martial and Marcus Rashford have shown plenty of potential, clouding the 33-year-old's possible role in the team.