There's 2 irreplaceable players in the world, that's Ronaldo and Messi.
Within some teams, there are other ones, like Iniesta on Barça, that are pretty much irreplaceable considering the team's vision, playstyle, and general philosophy. Right now, no one could do it like Iniesta does it in Barça. No one has had the time at the club to embrace their philosophy, and honestly, not many have Iniesta's quality to begin with.
Outside of these cases, I could see Messi being irreplaceable anywhere in the world. He has not proven himself in different conditions, but it's by his choice of staying with Barça. But he's honestly good and would do amazing in any top team. Ronaldo has proven himself in 2 clubs, with nearly every season outdoing himself, save for 2 seasons I believe, out of like what, 8.
They play in a way that's beyond the norm. Everyone else does something that's been done before by many players. These 2 guys do something that hasn't been done before, or has been done 50 years ago, when football was another game and games ended with ridiculous scores.
Messi is a beast that scored like what, 70 goals for Barça last season. Ronaldo 60, with a few games less. Ronaldo beat the record for goals scored in La Liga 2 seasons ago. This season, Ronaldo added another 5 from that, 45, and Messi, even more incredibly, added another 10, scoring 50. Messi scored 5 in a CL game, an all time record. Ronaldo scored against every team last season in La Liga, yet another all-time record. They've performed consistently for at least 5 years, improving nearly each year their stats. Other people (including you know who for RM and then BM) have great seasons, some have it one year, some have it for 5 years straight. These 2 guys have incredible seasons year after year, and then on top of that seasons that are above nearly anything done previously on football. That's the difference.
Against facts there are no arguments on the Robben case.
