He had to leave. Even if for just the exposure to truly world class talents.
I believe any footballer with any sense of ambition has to strongly consider moving whenever either Barca or Real come calling, talk less of when they are at a team like ours is currently.
When your kids and grandkids and great grand kids are watching replays of the spectacles called El Clasico's sometime in the future, after dinner, and marveling at the skills of a Zidane, or Ronaldo or Messi or Figo or Beckham, etc, it'd be nice to have the camera pan past you on it's way to the manager, so you can pause the tape and geezerly, toothlessly, mumble: "There I am. Right there.. In the corner, next to my best bud, Casillas. Let me tell you kids a story about Iker Casillas. See, Saint Iker as we fondly referred to him in the dressing room was really quite the rogue..".
And, seated there on your favorite armchair, you begin to relate your story for the zillionth time, fart contentedly two minutes into it, and then drift off into satisfying Blaugrana/Merengue induced slumber.
Heh.