I do not understand running a post up for Barnes against Dante Cunningham. Cunningham is 6-9 and has played most of his career at PF. He plays more in the post than Barnes does. The advantage there is Barnes' quickness. Get him coming off a screen and see if Cunningham can keep up with him. I bet Barnes gets good looks that way.
Pelicans defensive matchups are all over the place. One possession, it's Cunningham defending Harrison Barnes. Next possession it's Ryan Anderson defending Barnes. The possession after it's Anthony Davis defending Barnes. Messy. And you definitely do not want Davis out the three point line defending Barnes unable to provide interior defense & rebounding. Gotta do a better job of getting into defensive matchups in transition.