This is one of those classic ones where people use stats really badly. People look at the fastest speed any player reached and say they were the quickest, when in reality that's probably not a particularly good indicator of how fast someone really is in the context of a game of football. All the top speeds will have been reached when a player had been fully sprinting, without the ball, for about 30 meters, maybe more, not a very common occurrence in a game of football. In reality football is far more about how quick you are over 5-10 yards, which has nothing to do with top speed and everything to do with acceleration. Phil Jagielka might get a higher top speed at some point that Leroy Sane, but Sane is leaving him for dead all day on a football pitch.
The classic example being it was commonly repeated that Thiago Ilori beat Cristiano Ronaldo's 100m record at Sporting, so he was quicker than Ronaldo. But anyone who's ever watched the two play will tell you Ronaldo is far quicker. There was some similar thing about Javier Hernandez being the quickest player at the world cup, but in reality on a football pitch his speed is nothing to write home about.
The classic example being it was commonly repeated that Thiago Ilori beat Cristiano Ronaldo's 100m record at Sporting, so he was quicker than Ronaldo. But anyone who's ever watched the two play will tell you Ronaldo is far quicker. There was some similar thing about Javier Hernandez being the quickest player at the world cup, but in reality on a football pitch his speed is nothing to write home about.