Despite being the most common personnel group, 11 is not always the most efficient. Both 12 and 21 personnel have higher success rates (49% and 50%, respectively) than 11 (48%). While this is not a significant amount, it does show how players have evolved to take on multiple roles and maintain an offense's ability to run their plays out of multiple formations and personnel groups. Tight ends are developing more receiver skills, and receivers that can block are becoming more valuable.
Teams like the 49ers (38.4%) and Dolphins (44.8%), who run 11 personnel at a below average rate, while maintaining a top-five EPA, are able to find success because they have specialized players that allow the offense to consistently attack the same way with different players out of different looks. On the other hand, the Rams (93.1%) run 11 personnel at the highest rate in the league and find themselves in the top ten in EPA as well. Their success comes from their players' versatility and ability to perform in multiple roles, allowing the offense to attack in multiple different ways from very similar looks.
