Been over this repeatedly in the Ndombele thread, but...
I don't really have any doubts about Ndombele on the ball. He'll have poor games, but if we get him the ball in even decent positions he'll deliver. His talent and ability is for me beyond question.
There are essentially two ways for him to fail. Not doing enough defensively because of a lack of stamina, effort or attitude, whatever. Or, because we don't get him the ball in decent areas.
Villa game he was poor on the ball, that happens, but the other factors were there. Work rate, getting on the ball in good areas. Kept trying. The kind of "don't worry, I'll come good" kind of performance I like to see from a talented player.