Why would you associate Carroll with Benitez? Benitez left Liverpool the summer before they signed him.
I rate Benitez higher than most people do, because I generally approve of how he sets his teams up. He's easily wound up, though, which is definitely something that has to count against him.
Don't think Benitez has any track record of playing three at the back, so could see some big changes at Napoli this summer if they change shape as well as try to replace Cavani.