One night this weekend, a couple friends came over to the apartment to hang out, and--inevitably, I suppose--we started playing 5 on 5 pickup mode on NBA 2K9. The first game, my buddy picked five players from the Internationals list: Nash, Manu, Dirk, Pau, and Yao, while I went with a mishmash of stars from the 60s through the 90s: Big O, Doctor J, Pippen, The Dream, and Shaq (Orlando Magic version; he's modeled circa 1995).
Because we were just messing around, notice that we adhered to general principles of lineup construction. Point guard. Shooting guard. Small forward. Power forward. Center. Except that Manu plays the point role a lot for the Spurs. Same with Pippen and the Bulls. And Dirk plays like a three at times and like a center at times and is a power forward in the box score. And Olajuwon isn't really a four, though he certainly was lithe and a leaper like we think of fours today. And Oscar Robertson would probably play the Iverson/Arenas role these days, an undersized two with some point guard responsibilities.
In other words, if we were to construct the best possible team, specific positions wouldn't really matter. I've alluded to this before, when thinking about how to build the best offensive squad and the best defensive squad possible, but perhaps it bears some specificity.
I like to think about players as belonging on a Point-Swing-Big spectrum, rather than in one of five categories. You can think about Boris Diaw as belonging in the small forward, power forward, and center columns, or you can think about him as a line segment stretching from somewhere on the Point side of the nebulous Point-Swing border and stretching a step into Big territory.
Here are some examples: