Well as bad as you think Walker was he still won the most tackles for us and completed 94.1% of his 101 passes; only Foden had better completion stats but made less than half the number of passes.
I also though his recovery pace was useful on occasion.
That foul was daft and he did play conservatively but I'm not sure he jammed Torres in: I think Torres did that himself and is still getting to grips with our positional play game whereas Walker knows it inside out.
Pretty sure he did create at least one thing on his side with a brilliant long ball that put Torres away.
Canelo is though a different proportion going forward but he still is not as good as Kyle defensively and our current success is built on our defence so I see Walker as remaining important to Pep; plus Cancelo can play on the left, where he and Zin must be ahead of Mendy.
Walker was doing his job as part of a back three today and I'm guessing Pep will have been quite happy with it.