An overall rating is a common element in sports video games, including NBA Live and NBA 2K. It is intended to be a representation of a player or team's overall skill and value, and by extension, their relative ranking in the league.
In the early days of basketball gaming, overall ratings were a hidden attribute, as they served no real in-game function. As season and franchise modes were fleshed out and AI-controlled teams given the ability to reject trades, they gained significance and thus began to be displayed in the games. The maximum overall rating in most games is 99.
Overall ratings are calculated using a player's individual ratings, or in the case of teams, the ratings of all the players on the roster. The formula to calculate overall ratings has varied between games, which has led to inconsistencies in the way that player value is represented. For example, an overall rating of 85 might represent a second tier All-Star in one game, and one of the top five players in the league in another. As the years have progressed, efforts have been made to further differentiate players, and reserve overall ratings of 90 or higher to the best of the best.
A common problem in the calculation of overall ratings is the lack of appropriate weighting for certain individual attributes, particularly athletic ratings. This can result in certain players appearing to be overrated or underrated, with some of their individual ratings artificially increasing or decreasing the overall. As such, there is a certain lack of precision and accuracy in overall ratings, and it's generally not been possible to achieve perfect results in terms of ranking and rating players.
One of the main purposes of overall ratings is to reflect a player's overall skill level and rank in the league, at a glance. Gamers can immediately identify the best players on a team or in the league, simply by looking at their overall rating. It also provides a succinct summary of a player's value, relative to their peers.
In terms of the game's mechanics, overall ratings and their implied value are significant in franchise modes such as Dynasty, Association, MyLEAGUE, and MyGM. The AI will take a player's overall rating into account when evaluating the value and fairness of a trade offer, and will also generally only make offers that include players with similar or equal overall ratings. As franchise modes have become more sophisticated, other player attributes have become important factors, but overall ratings remain the starting point for evaluating player value in trades.
Criticism & Controversy
Although overall ratings are significant and do serve a purpose, their importance is sometimes overblown. As mentioned above, the method of calculating overall ratings is not always ideal, and players may end up appearing to be slightly underrated or overrated due to certain individual attributes being unsuitably weighted. As the individual ratings and other attributes are far more important in determining a player's level of skill and style of play, it's more important that they are accurate, rather than being fudged in order to make the overall look "better".
It has been suggested that overall ratings should be a hidden attribute once more, to eliminate this problem. However, the suggestion is generally unpopular and seen as unfeasible, since overall ratings are still important, and serve a useful function.