How can Wilson Audio speakers sound that good if they are using OEM drivers?

Kost 

I don’t recall any Wilson with a Focal midrange driver - the first ones used a Seas inverted surround - Focal Kevlar tweeter Dynaudio poly woofers - which maintained through the whole WP thing. 

From the WP5 up the midrange was ScanSpeak 18Wx5x5 and the Focal inverted laminated TI dome. 

Good listening 👂 

Peter

 can do the math ( slowwwwwwly ) and I can figure out why they might have to wire that fantastic  midrange out of phase after screwing it up with a steep slope crossover

Wilson is akin, IMO, to a fully tricked out Corvette. You can make it really fast - even faster than production - and really luxurious. It's super awesome . . . but it's still a Corvette. Front-engine, V-8, there's only so much you can do.

Wilson takes great pains to trick out their cabinets - some of the best in the business in terms of vanishing low cabinet resonances. Also, they really do a good job listening to tweak the passive parts from the binding posts to the crossovers. The end result is an awesome product. But you can only do so much with, what, a 6" midrange made from paper, fiber or plastic. All those gains in the cabinet are given back with the sub-optimal drivers.

or in a midrnge driver frame, magnet, and structure that reflect back 70% of wave...right thru the cone.....

i recall somebodys patent expiring.....

lots of engineers talk a good. game about system engineering.....i know these things on beasts with over a million parts.....

and have been humbled....