I have always wondered what the value of Assist-to-Turnover Ratio was. More specifically: Why that particular ratio? I understand that it is supposed to be indicative of a player's ability to make good decisions with the ball, but I cannot figure out how this ratio is a good way to measure that. What it basically tells you is how many Assists a player has per Turnover by taking a player's total Assists and dividing it by his total Turnovers. Not that Assists and Turnovers are completely unrelated events, but they hardly have a cause-and-effect relationship like, for example, Field Goals Attempted and Field Goals Made.
I know you all know what these stats are but I think it will help frame the discussion:
Assist: This is credited to a player that passes the ball to another player that makes a field goal. More specifically, the pass has to "directly lead to a basket" or be given to the player attempting the field goal in a position to score. What is the letter of the rule? I've heard two steps and I've heard two dribbles as far as what the offensive player can do after the pass and before taking the shot. Find me a better definition and I'll make you a dope-ass webpin.
Turnover: Basically, if the player has the ball and then loses possession of it to the other team (without scoring or being fouled or the quarter clock running out etc . . .) or if the player's team has the ball and that player commits an infraction (like an offensive foul or 3-second violation) that causes his team to lose possession of the ball, that player is credited with a Turnover.
So how are these two things related?
To the extent that a player can commit a Turnover attempting an Assist either on the pass or a "pass-and-crash" foul or (and this is a stretch) while trying to get into a position so that he can have a better angle at attempting an assist.
So how are these two statistics completely unrelated?
The answer lies in listing the myriad of ways a player can commit a Turnover without attempting an Assist:
- Dropping a pass (see: Foyle, Adonal)
- Moving/Illegal Screen
- Committing a charge while not attempting an Assist
- Dribbling the ball off his foot
- Having the ball stolen either on a pass, dribble or just holding it (non Assist situation)
- 3-second violation
- Stepping out of bounds (see: what GSOM's widely held untruth about MP2 2007/08)
- Traveling, Carrying, Palming, etc . . . (see: Players, NBA)
- Etc . . .
Dependant versus Independent:
The other thing that makes these statistics very different is that Assists are completely dependent on another player's ability to convert a field goal attempt.
BRICK BROS. We eat Assists for breakfast.
Whereas Turnovers are mostly independent of other players to the extent that anything on a basketball court can happen without regard to the positioning/activity of the other 9 players on the floor. I would say that over 90% (observational only) of Turnovers are completely preventable by the individual credited with the Turnover.
Get me the rock!
So why do they measure Assist-to-Turnover Ratio and how does that Ratio tell you something about a player that is useful that could not be garnered by looking at Turnovers and Assists per 40 minutes, side-by-side?
So my questions are:
1. Why does Assist-to-Turnover Ratio exist and why are two, mostly unrelated statistics, displayed as a ratio?
2. What predictive or other value does this statistic have?
3. Wouldn't Assist-to-Steal Ratio make more sense? At least this would measure how many net possessions a player is worth.