#3 Paco Alcacer

The former Valencia striker was signed for an obvious purpose last season, to provide backup for a tired Luis Suarez, but Alcacer just hasn't done enough when called upon. He scored 8 goals last season at that club, but only has 13 in total in his year and a half-long stint at the Camp Nou so far.
Once regarded as Spain's future main front man, Alcacer has struggled even making appearances from the bench for his club this season.
It's unfortunate for the player and says a lot about how difficult it is to get into a rhythm with other attacking players when one not in the starting lineup. Alcacer is also just 24 and can definitely find form again but it seems unlikely that he'll fit into Barcelona's team anytime soon.
Plenty of Spanish teams would be interested in him, perhaps even his old club Valencia, so Alcacer would be better off leaving when he can still command a decent price.