ORtg levels are in the same ballpark as team efficiencies—100 is approximately average, higher numbers are preferable. While on the floor, the typical player will use 20% of his team's possessions. The bulk of participants range between 15% and 25%. An ORtg over 110 indicates that the player is effective at getting his teammates involved in the offense, while someone with an ORtg under 95 is likely to have difficulties finding ways for others to score. In addition to being able to shoot the ball, players must also be able to defend against pick-and-rolls, where guards face up court against smaller forwards or centers. Players need to be able to protect the rim, and they also need to stop other players from scoring. Finally, they need to provide help defense if their partner goes down the court. In general, players with high ORtg values tend to be more efficient scorers, while those with low ORtg values tend to be better defenders. A player's overall impact on the game can be estimated by combining their shooting and defending abilities. A perfect 10 would be able to hit every shot and block every attempt at the basket. In reality, few players are capable of such dominance, but we can still estimate what kind of number would make them successful by looking at the players who have been most valuable over time.