I think considering the recent games we saw from both teams in La Liga, Atletico Bilbao can win this game and beat Villarreal. Because in the last five games they had against each other, Villarreal never won a game against Atletico Bilbao and Villarreal lost the last game they had with a 1-0 result in this season.
Villareal is a strong team right now. There's no doubt if bilbao will be losing against villareal. Villareal is still trying to defend its place to be qualified for europa league. That being said that if it will be so hard to see bilbao to beat villareal. 
Bookies are favoring villareal at this moment and that's a sense thing for sure caused by villareal is far more consistent compared with bilbao. Bilbao may lose full points against villareal soon.
Villareal will be playing at home. It doesn't even make sense to pick bilbao to be a favorite club in this match.
It's easy money for people who pick villareal. The gap is quite big in the current standing. Villareal is still superior based on the current statistic in la liga.
Athletic Bilbao is having troubling time but still they can fight back with have chance for the sixth spot because few teams are on decline in performance and things can change into any game Villarreal was good in early half of this season, but sadly they lost their momentum and now having troubling time which bring them down even many were feeling they will finish into top five strongly.