New boss Unai Emery also wants a forward, but to achieve that they need to sell Bacca.
Bacca has two years left on his contract, but Villarreal know they will struggle to get a transfer fee because of his age (33).
According to Marca, Turkish side Besiktas have sounded out Villarreal concerning a possible deal for Bacca.
Besiktas will play in the Europa League this coming season and are looking for a new striker.
The Istanbul club are studying the idea of signing Bacca on loan after being offered the player in recent days.
During his three seasons at El Madrigal, Bacca’s performances have steadily worsened.
From 18 goals in his first season, his goal return dropped to 11 in his second year, and just five strikes in the most recent La Liga season.
Bacca is settled in Villarreal with his family and will not accept an exit unless it satisfies him.
For that reason, the 52-time Colombian international has ignored offers to play in exotic leagues like the Chinese Super League.