We ran at a £9m loss with those wages on the balance sheet. Of the five you've named Moyes alone earned £3m a year - it's not a stretch to beleive that Neville and Heitinga were both on £2m a year so yeah, call it £10m a year.
But Heitinga HASN'T left. And we've hired Martinez and his entourage. So we've only ACTUALLY reduced that £10m wage figure by the total value of Mucha's, Hitz's and maybe Neville's wages - how much do you reckon that is? £4m maybe?
In conclusion, we've cut our expenditure by £4m over the year. Last year we lost £9m, so this year we'll lose £5m if NOTHING ELSE changes.
So no, we don't have £10m to spend as a result of Moyes, Neville, Mucha and Hitz leaving. We've simply reduced our losses a bit. We have a £44m (approx) debt which is growing by between £5m and £9m a year. On those figures, we NEED to sell Felli in order to improve the squad - he earns between £3m and £4m a year AND we would pocket £23m-ish. So we would reduce our outgoings by the value of his wages AND generate a pot of money with which to pay for the purchase and wages of more players.
It's simple maths, nothing more.