It prefers positions for newer managers who need some assistance on where to put players as well as all managers who are viewing other rosters. If you see a team with 5 listed centers and no SFs or PFs, you can assume that they are more inside based, same goes for guards, if you see that they play four shooting guards or something at PG/SG, then you can confirm that they might play outside tactics. It just helps with game planning and thinking about tactics dealing with other teams. If teams got to choose their preferred positions, I have a feeling many managers would just list every single one of their players as the same position so that game planning is harder for their opponents. As for the JS, JS is rated as one of the distinguishing skills between a PF and a C, Centers generally have less JS than PFs do, so if you train him to have more Jump shooting (although you may not be able to based on his age), his position would likely change, if that makes sense.
Murray/Harris/MPJ/Grant/Jokic - 2020 NBA Champs