Does this guy have options ? I know as a rule 5 you can't option him down, but you could next year if he has options . Has me thinking, perhaps next year, and every option year , or years following when he clears waivers, you could stow him away in AAA, get him lots of rest at the end of the year, and if you make the playoffs, he'd be a good 1 inning pitcher in close games for a couple of series games. perhaps setting him to 10/15 and you could get 2 appearances in a series, 3 over 2 series or something. that might be the best way to go about him if his skills are great.
Maybe you only get 30 innings out of him a year, but if you can leverage those such that their impace innings in the postseason, that would seem to be the best plan. That of course assumes you feel pretty confident about reaching the postseason the next couple of years. If not, could be an idea to sell him to a contender for a useful prospect.