It's the fact he's one of the best managers around and he would attract quality players across the globe. I don't expect him to sign 'superstars', but players who are underrated that can be the golden spine of the team. I have faith in his ability to adapt to our situation and build us into a lethal force where we could possibly give the 'top 4' a scare. I don't think none of us expect him to win the league, especially in his first season. When he does leave us, another quality manager may be interested seeing as we were worthy enough to attract Carlo and it could follow suit. He comes across as extremely likeable as well. No arrogance or none of that BS.
Capello is a different situation because he's limited to English players. Carlo can still attract a few quality players I bet.
Those are my points anyway.