PG is the only position (imo) in basketball defined offensively but even it's definition isnt as defined anymore.
In the latest Jass season Raul Neto was the PG for the first half of the season, but really Hayward or Hood was more of the PG in the half-court offense while Neto most frequent traditional PG duty was bringing the ball up the floor. His role on the team as PG was more defined through who he defended.
Saint Cy of JFC, I've read your answer and the following arguments by other people and I take back what I said... to an extent. Please allow me to think out loud this issue in order to explain myself in a tongue that is not my native one.
Personally, I'm not prepared to agree that a player's position is defined defensively but I'll give you that the way an actual NBA offense works often doesn't match the alleged position of the players. Let's think for a moment about the Bulls teams of the first three championships. Were either BJ Armstrong or John Paxson PGs? That offense worked with either Pippen or - less often - Jordan bringing the ball up the court and setting the plays up. Paxson and Armstrong mostly spoted up, hoping to be open when the double team closed on one of the stars. So, regarding that particular offense we can say, truthfully, that either Pippen was the de facto PG or that there was no PG. This means the allegation that Armstrong's and Paxson's were the team's PG was either a result of their defensive assignments or... something else. But what? I would argue that existed - and still does - some sort of "default standard" in which the shortest player is automatically called the PG. Why I say that? Because even though Armstrong and Paxson, both standing at 6'2, were shorter than Jordan, they were clearly less mobile than him, which meant Jordan ended up guarding opposing PGs with regularity.
That brings us back to Raul Neto last season. Did he really play as a PG offensively? Most of the time no. Did he guard the opposing PGs? Almost always, if I remember it correctly. So, how can one define his position, after all? Offensively in reality he was just a cog, since he wasn't either asked to shoot or set up plays often. According to basketballreference.com, though, he played PG 100% of the time, which means he was either that sort of "PG by default" by being the shortest player on the court or a "PG due to defensive assingment".
In summary, I think there are three principles in operation here and one of them is picked by the coaches and color commentators according to the situation: the first and probably the oldest, is "a player's position is defined by what he does offensively"; the second is something like "the PGs are the shortest ones and the Cs are the tallest ones and there is a position scale from 1 to 5 according to height/size"; and the third one is "who a player guards is his position". I think people try to solve most issues with the first principle and if it doesn't work, they try the second... and then the third.
So, concluding, what is in question here not only has something to do with the way people analyse what happens on court, but is also a rethorical or argumentative matter. In other words, it is also a discoursive issue.
