Josh
Looking in "Rare Birds of North America" by Howell, Lewington, Russell (2014 Princeton University Press), in the account for Piratic Flycatcher they write
"Similar Species: ... Variegated Flycatcher, another austral vagrant, is appreciably larger with longer bill (pinkish below at base), flattish crown slightly peaked at the nape (versus more rounded head of Piratic), slightly flared whitish eyebrow, bolder rufous edgings to uppertail coverts and tail, and paler underparts without bright yellow wash; often perches lower and in less open situations than Piratic."
They do not mention pale edges of any wing feathers as a field mark between these two species. In their illustrations of the two species side by side, Piratic is shown with quite crisp and bold white edges to wing coverts and remiges (as is Variegated). BTW this book has awesome illustrations by Ian Lewington. A fantastic reference book
Good birding,
Derek Hill
currently OH