Although it seems that the potential signing of Leandro Cabrera has fallen through, Villarreal are keeping a few options on the table in central defense (finally!). As noted here a few days ago, Cesar Arzo could be brought back into the fold, if things work out properly. Villarreal have also apparently been looking at Juanito (Betis), Pablo (Atletico), and Nasief Morris (Recre), as well as Marcano (Racing - leftback).
I trust Pellegrini and Llaneza, but I have to say - the thought of bringing in defense from Atletico, a pillar of horrible, horrible defense - is a little unsettling.