Supposedly Frost was interested in being a defensive position coach when Bo was hired here, and Bo wasn't interested in him. 'not seeing eye to eye' is the phrase often thrown around, not sure if that specifically relates to Frost as a defensive coach or just as a coach in general.
Frost has a good thing going at Oregon right now though and I wonder why he would even want to leave it. He needs more years of seasoning before moving up any more, and where better to do that than at Oregon? Coming here to run Bo's show seems like it would be the kiss of death honestly. If/when Chip ever leaves Oregon, then think about a lateral move to get even more experience, or try to rise up through the ranks somehow.