Hard to say, maybe mind games, or personal thing for him as we have seen videos of their confrontation years ago. And it seems the Benavidez are hell bent on getting their revenge on Caleb. But the thing is that Caleb saw this as just their antics and so he will be more prepared for this fight just to make sure to shut the mouth of David and his father.
Both fighters are eager to win for a chance to have a shot for Alvarez, winning these fights will give them the hype for their career, for sure both of them are preparing and anticipating how their opponents are adjusting to bring everything once they are already inside the ring, whatever the reason from both fighters they will use it to fight in more inspiring way.
Winning is the goal to bring more opportunity in their career. Whoever will be the winner deserves the credit.