Danny Duffy is not a reliever, but he's a good reliever.
Deal with it.
He throws fever and contours. He likes to scream. He might literally explode at any moment.
That sounds like a reliever, doesn't it?
The immediate concern that arose when Duffy wasn't awful last night was something that could be described in one of two ways. You could call it The Aaron Crow Effect if you wanted to cast a judgmental shadow over Duffy's folding chair in the bullpen. You could talk about value and how the if-it-ain't-broke-don't-fix-it approach is an excellent way to squander a potentially impactful starting pitcher.
Or you could call it The Luke Hochevar Effect, and smile antipodal lasers into the souls the hopeful. Which is to say, you could argue that Duffy hasn't done anything useful in his career as a starting pitcher, and if he can provide the Royals with some more disgusting relief appearances like he unleashed last night, that might be the role that suits him best. Of course, the Crow Effect folks would probably cite Duffy's success as a starter last year, and maybe the year before as well. But those were both samples of less than 30 innings, so they might not be an exceptionally strong basis for a counterargument. (Then again, some Royals fans love citing small sample sizes. See criticism of Billy Butler, Mike Moustakas, etc. for examples). Duffy also owns a less-than-heroic 3.74 ERA as a starter in Triple-A, 4.68 in the majors.
He's only 25, though. And his stuff is gross. I can't say I'm personally on the fence on the matter in any way. He would absolutely provide more value as a starter. The Royals can also fall back on a bullpen role if he has some kind of mental blemish that prevents him from succeeding in the rotation.
It might seem obvious to some, but it has happened before. James Shields and Bruce Chen might not be around next year, and while Kyle Zimmer might be, having multiple options for the rotation is preferable to having the left side of the bullpen checked off of the to-do list.