I think one of the reasons why Rafa got this job is because of Bale, Rafa knows him very well from his Premier League days, he can speak pretty good English as well as Spanish and Perez wants to see some kind of return from his 80 million signing. It's one of the reasons why Rafa got the job at Chelsea, because Roman wanted to see more from Torres and Mata, 2 players that Rafa was affiliated with.
Apparently if Rafa was to stay at Napoli, he had already outlined plans to buy Pepe and a couple more Madrid players anyway.
It's reported that Yesterday Rafa outlined a plan to use C.Ronaldo as a Striker with Bale just behind, will be interesting to see how that works.