I have also played the game a long. I am also a coach. I happen to coach the spread system and have for the last 4-5 years, after learning it at a clinic directly from Coach Underwood, then learning the sets he runs out of at the same clinic 2 years later, directly from Coach Underwood, and had a side conversation with Stephen Gentry about finer details. This is on top of watching his championship productions DVD at least 50 times over the past 5 years and youtubing his games and other clinics where he taught spread. I think my spread knowledge is pretty solid and "misconceptions" are minimal.
There is no 4. There are the 4 players outside, and they are interchangeable. The only guy who you can maybe say is different is the PG because he has the responsibility of making sure everybody is spaced properly and choosing the entry based on what the defense is doing. But once it starts, he becomes interchangeable too. Don't believe me? Fine. That is from Coach Underwood himself. Quoted, paraphrased, whatever. In person, on DVDs/youtube videos, whatever. Depending on the flow or entry chosen, the guys who start on the top might end up on the wing or vice versa. Guess what? Nothing changes. Once the ball hits the wing, cutter 1 (opposite slot) cuts to the basket and the ball side corner, cutter 2 (opposite wing) cuts to the low block for a post up. The strong slot and the pinch post make the read for the 2 man game if the cutters aren't open. Doesn't matter who is there. If TJL ends up in the cutter 2 spot, he's gonna post up. If Leron ends up in the strong slot, he's going to (and has multiple times already) initiate the two man game.
After the 2 man game, everyone else fills back around the same 4 perimeter spots. If there's a drive baseline, the guy who was cutter 2 posting up, will then drift out to the corner for a kickout 3. Talk about that difference traditional position skill sets, and that's the same guy doing those things back to back.
Defensively yes, it matters more. Offensively, it does not. Yes we're doing certain things based on our roster limitations, changing the basics of spread is not one of them.