I get that he was a striker in the youth team, but I do think you can get swallowed up in the middle as a striker in men's football. I would rather Greenwood were on the wings where there's more space to make an impact and he can be involved for 90 minutes, instead of on the periphery trusting his teammates to get him the ball.
I wouldn't even mind if his longer term position was at RW, he's clearly very involved there and has more dynamic choices that at striker where sometimes it's a thankless job, especially against those very deep defences where you need patience for 90 minutes. Look at Martial, he's learning more and more to stay closer to the goal and although he's getting more opportunities, he's on the periphery a lot more unless he drops deep or exchanges with Rashford; he can't do the dribbles he used to. I wouldn't hurry to put Mason into that situation as his overall game is quite good, and it would be a bit of a waste at this stage.