Following Marcelino's call not to sign a contract extension at the end of last season, the club opted for change in Castellon, as Perez made the move from Rayo Vallecano.
The 38-year-old had developed a superb reputation in Vallecas, leading the club to a UEFA Conference League final in May, but he accepted Villarreal's offer with the challenge of managing in the Champions League.
However, he's won just three LaLiga games from 11, and claimed one victory from four in Europe.
The latest frustration came via 6-0 humbling at home to defending European champions PSG, and club owner Fernando Roig is now considering Perez's position, just being just months into a three-year contract.
If he can secure positive result at home to Getafe over the weekend, that could offer some respite, but Villarreal are planning their next move carefully.