Rooney was good the first couple of matches, has been dreadful since, and is most assuredly NOT making the players around him better (which was supposed to be the whole point). He could be useful as an impact sub, if he'd accept the role and have some positional discipline, but Koeman seems to have interest in neither, and I suspect it has something to do with his having been a star player who likely felt people should have deferred to him, even late in his career.
I am quite confident any number of players could have converted that penalty, even the much-maligned Sigurdsson. Every ratings thread I've seen anywhere still gave his performance a "5" - wholly unacceptable. You can't anchor your team around a guy in his decline phase who is giving you 5s and 6s week in and week out, who is also possibly preventing Sigurdsson from settling into his role in the XI. Only one of those two might be a part of the next decent Everton side, and it's clear to eyeryone with eyes to see that they can't play together on the pitch.