Often shortened to winshr, winshares are a measure of basketball productivity. Essentially, it credits each player for their contribution to team performance, allocating team wins to each player according to their valpct: (valpct*team wins) The idea is that each player is responsible for some of his team’s production, and that team’s production results in some number of wins — if a bad player is responsible for a large valpct, team wins will be lower than if a good player was in his place, this difference is reflected in winshr. This measure is useful in attempting to determine value, as it is a more flexible way of determining the “best player on the best team”, leveling the playing field for good players on great teams and great players on good teams, for example. See also this background.
I am aware that this measure is imperfect, especially since it has no way of taking into account whether a team’s wins and success come while the player is on the floor or off (which is especially significant for injured or traded players). For this, a better statistic is probably plus/minus, but here at the Arbitrarian, we usually stick with box score stats, which are usually easier to get a-hold of.