I think you massively underrated him tbh, there are very few all round players like him that constantly put in 7 or 8/10 performances. Not hard to see why Pep loves him.
How often do you see the likes of Kante and Matic ping a 40 yard ball over the top of a defence for a striker to head in.
I think I rate him quite fine. I'd put him in the Premier 11 with Silva, Debryune, Sterling, Otamendi and Walker as shoe ins. With Delph, and Eddie dangerously close too.
I just don't think he is uniquely special. Clearly the system has made him look great. He's always been a very good player... He he isn't so special that he'd be hard to replace. Why do I believe this?
Simples. Watch Dihno from last season. He wasnt half this good. So clearly learning the system helped his game. There are equally talented players who can do the same.
I mean, there was a thread this summer called getting the DM position right. That thread was started partly because of how average Dihno's play was when learning the system.
David is special, Yaya is special, Kev is special... Dihno is not! He is a good player, playing great football.
But even now, there are still quarks in his game. His passing in tight spaces is probably the weakest of all the starters. And on many occasions he has been the main culprit of a loss of possession under pressure. Some of that is just fatigue, some of it is not been as cultured as the others.
So I say this having watched him judiciously in many matches. Noting both his strengths and weaknesses. He is good. He is not special. Thus, replacing him contrary to popular opinion will be comfortably doable.