Assist Percentage is the percentage of all field goal attempts assisted by the player while he/she was on the floor. There is no corresponding team percentage because it would be 100% in all cases. In 2017-18, John Wall led the NBA at 49.6%. The other leaders shouldn’t surprise anyone – Lebron, Westbrook, Harden, Simmons (shout out to Abilene) – so it passes the eye test. The question is why should you care about this stat?
Well, when you’re looking at assist percentage, you have to consider style of play. If you run a great deal of isolation plays, you can’t expect anyone on your team to have a very high assist percentage unless like the Cavaliers and Rockets, that person with the ball can kick out to good shooters. If you have a high paced offense, you should also expect this number to be fairly dispersed since there’s probably quite a bit of ball movement allowing for more people to have a hand in assists.
Another consideration is the usage percentage stat. That’s an estimate of plays used by the player when they’re on the floor. It takes into account field goal attempts, free throw attempts and turnovers. If you have a player with a high usage percentage but low assist percentage, that is usually not a great sign of success. For example, Carmelo Anthony had a 23.2% usage percentage and 6.5% assist percentage this past season. And the Thunder were not thrilled with his contribution.
If both numbers are healthy, that means the person with the ball the most is doing good things with it – James Harden was at 36.1% usage and 45.1% assists. He also average 30.1 points per game and if he’s not MVP, something has gone horribly wrong.
The trouble with this stat outside of the professional level is the trouble with the assist stat in general, the reliability of the statistician. You’ve definitely seen scenarios where someone averages more assists at home than on the road or at the small college or high school level, the point guard is given more assists because the spotter at the table misses who made the pass and just defaults to him or her.
In conclusion, assist percentage is a very useful stat but like most other statistics, you have to put it in the right context for your team to get the most out of it.