He doesn't actually need to score provided he continues to be part of performances where the team scores. Honestly, if he'd never been introduced to us as a striker but rather as an attacking midfielder, he'd be much more highly rated. It's only this expectation that scoring lots of goals should be part of his game that holds back his reputation. See him as an all-action, creative, pacy, flair AM and he fulfils every requirement magnificently.
And I actually think it suits this formation to have one proper 'striker' (Rooney) and one more all-round attacking player (Welbeck) playing ahead of the playmaker. Obviously we'll have to see what it's like fitting RVP in next to Rooney - maybe with RVP as the 'striker' Wayne can become the 'all-round attacker'. But I wouldn't be at all surprised if we struggle at first with those two, without that player running around making the spaces, linking up the play and winning the ball. Arguably that position might be well-suited to Januzaj as well.