If you don't spend 15-25 million on a player every year, it is hard to sustain a team with players of "top top quality". Even players from the "smaller leagues" who exhibit high quality command such fees nowadays (Modric, Fellaini)
Our problem has been that we've never dared to compete for players in this price range lately.
With the recent boost to the coffers, there is no excuse for not doing it anymore.