Only was able to watch the middle session and the start of the 3rd session (don't have proime so had to rely on less than legitimate means), so I can't claim to be able to judge anything outside of that accurately, but from what I did see the pitch had a bit in it and Rabada was bowling excellently, so this whole the sky is falling in chat is going too far as usual.
The main reason why I was (and honestly still largely am) supportive of the top 3 in this game is down to having even less faith in any realistic alternatives. Khawaja obviously has credits in the bank, although I do worry that some of his struggles against first Bumrah and now Rabada are a sign of Anno Domini catching up with him, Marnus and his form I have obviously discussed here a bit and this innings changed nothing in my opinion, neither a clear success nor an unmitigated disaster, just somewhere in between. Green is a bit more of a concern however, 3 definitely feels a spot too high with how much of a shaky starter he can be but it is still vastly preferable to someone in Konstas who has less FC tons in his entire career than Green has in his recent Gloucestershire stint alone.
As for Webster, yeah he did look more than a little chancey early on, but that is clearly secondary to actual results, any technical frailties are far less of an issue at 6 in most cases than higher up the order. Also think his bowling might be handy on this deck, no real pace to speak of but his bounce and seam movement could be a handful if he gets his length right