My point is only that we do not have a model that says "top 4", as this is relatively irrelevant to us (maybe CL revenue of £30m a year? Less than 7% of our turnover). Our model is to get ourselves back to the top. Selling Welbeck to Arsenal does absolutely nothing to prejudice that goal.
Could it mean that for a single season we finish 5th instead of 4th? So unlikely that it shouldn't be factored into any commercial decision (I'd say Sanchez up top with Ox/Walcott to provide width is arguably better than Welbeck anyway).
You do understand that we sold Welbeck and replaced him with Falcao, that is an upgrade, that is something that improves our chances for top 4, not lowers them. You can ofcourse talk about how we strenghtend Arsenal by letting them have Welbeck and brought increased competition on ourselves, but you also have to realise that Arsenal could have brought in another striker (they were also in for Remy and Huntelaar and Zigic) if we had said no to a Welbeck transfer, so in the end that argument might not be as clear cut as many people think it is. It is not like Welbeck was their only option.
In the end I also think a club like United needs to believe in its own strenghts and qualities, what kind of weak excuse for a club would we be if we'd be trying to increase our chances on top 4 by weaking Arsenal. We are Manchester United, we are not supposed to be afraid of a little competition and we belive in our qualities and strenght to get the job done. If we get top 4 it should be because we are good enough to be in there and not because Arsenal aren't good enough to be in there. Also it is Welbeck we are talking about, player that was 3th or 4th choice for us, 26 goals in 4 years, it is not like we sold them the best striker in the league or something like that. If Welbeck to Arsenal would make us wet our undies in terms of improved competition than there would be something seriously wrong with us.
The only fair point is that we lost out an academy player that had alot of potential and mileage left in him and that in the long term we will miss out on the opportunity of having him lead our line if he'd develop into a good striker. Which is something that might result into us having to purchase a new striker within 2 years time when RVP hits 33 and will need replacing. But so what we have an exciting prospect in Wilson who strikes me as a more naturaly gifted striker than Welbeck and we also have Powell who might trun out to be a striker and Will Keane, and we have a shitload of money so if we do need to buy a new player in 2 years time than so what, it is not like we can't afford it.