Agreed a poor performance, but look what he was working with.
Guehi seemed out of his depth, Walker seemed off the pace (still injured, perhaps?) and James was playing at left-back for some unfathomable reason. Then second half they went to a 5, which Stones has rarely played, a CD 3 with Guehi and Walker then James and Saka as wing-backs pushing forward.
Add to that Phillips as a lone CDM, constantly either dropping back level with the CBs or else not in any real space, so he either couldn't be passed to or else every pass to him came straight back.
Stones played like what he was - a man who's had a frustratingly injury-ridden season, trying his best but desperately needing some rest and recuperation, playing in a poorly-organised side that was getting cut through like butter, with nobody further forward making anything happen.
He wasn't at his best, but luckily for him and us, Pep's never going to put him in that situation.