But that's where it becomes Premier League specific and over the duration of time spent playing in that league.
Arjen Robben was class for Chelsea, but played 3 seasons.
Jaap Stam was class, but played played 3 seasons.
You look at the players being mentioned, and they played the majority of their careers (and certainly at their absolute peak) in the premier league.
The likes of Xabi Alonso and Michael Essien are obviously excellent players, but Alonso didn't play in the league for long enough and Essien had two good seasons before being destroyed by injury. In contrast, Keane and Gerrard became premier league legends over a sustained period of time. Similarly Lampard and Scholes fall into that bracket.