Kaka is a great player, but his performances haven't warranted the praise recently. I mean, he finished very highly in both the Ballon D'or and WPOTY awards despite the fact that Zlatan has massively outperformed him in Italy for the last 2 seasons.
If you mean Borja Valero then he's already failed in England once with West Brom last season. I think he's back at Mallorca on loan, but from what I remember he was never suited to English football and was a total flop.
Looked classy as owt when I watched Mallorca the other day.
He never settled at West Brom though.