I've got mixed feelings but mainly due to how sterile it all felt, particularly in the first half. We had some space out wide due to crowding the middle but we couldn't really do much with it. But equally, West Ham are a dangerous side who are very effective on the counter and considering the results they got at home last season to win so comfortably is testament to how brilliant the system worked. They had no opportunity to slice through us or counter attack, we forced them to go wider because we had numbers in the middle and they didn't really know what to do, it wasn't something they were expecting so we just kept the ball. I'd imagine even if it was 0-0 with 15 minutes to go they'd have been spent having chased the ball and we'd have created opportunities with a subtle tweak in formation.
The inverted role has been something Pep's used with Delph, Zin and Cancelo (very effective from the RB role). Having both in there was new - at least I can't recall a game where I've noticed it! Walker is never going to be creating the way Cancelo can but he can keep the ball and it means that the opposition have to go long to try and get past us and he'll be there preventing runners from slicing through us and if Dias/Ake get beaten out wide Walker will be back in a central position to cover. Cancelo has the ability to beat a man and then play in Haaland or an attacking midfielder...
It's bloody genius on reflection!