Tel I'm not saying that he should be our first choice centre forward. What I'm saying is that he can and should be utilised in that position in certain games where he'll be able to play on the shoulder and have space to run into. Leicester couldn't handle him and Morgan could arguably have been sent off before he was. But he's not so good with his back to goal and last Sunday was a waste of his talent IMO.
When we play at home or against teams that defend deep leaving very little space, we should start with Tosun. He's a good player, but I agree I don't think he's good enough to help us break into top 6. So we need somebody to lead the line, link up play and, most importantly, slot most opportunities that come his way. There are very few who offer this who also are able to play on the shoulder. These are the very top strikers and wouldn't come here. A younger version of Giroud or Dzeko would be ideal.
That would enable us to have DCL as third choice. To continue his development from the bench and starting the occasional game through injury. If our main striker get's a serious injury and is out long term, then if DCL still isn't up to the task then we need to bring somebody in during the next transfer window. If DCL doesn't continue to develop within the next 2/3 years then we need to sell him on. He'll be 24 by that stage and could probably have a decent career at a club not competing for CL qualification. Plus we'll need that position as 3rd choice striker to bed in the next appropriate young player, hopefully from our own academy if there is somebody good enough, but if not brought in from elsewhere.
I know you don't rate the lad and he does have a lot to learn and improve before he's good enough to start regularly for us. But for his age, there's probably only Rashford who's ahead of him as a young English striker, and maybe only a dozen or so around the world. If he can develop into one of the top 12 strikers in the world then it's worth while keeping hold of. Not saying he will, but he's with the right manager in Silva so he has a fighting chance.