The 2013 Seattle Seahawks won the Super Bowl in part because they excelled at breaking tackles. Not only did they lead the league in broken tackles as a team, but their top rusher, passer, and receiver were all first or second at their position in this category. In 2014, they led the league again, and the running back and quarterback were exceptional for the second year in a row. They lacked the same physicality at wideout, though, and that might have cost them their shot at back-to-back championships.
Historically, we have defined a "broken tackle" as one of two events: either the ball carrier escapes from the grasp of the defender, or the defender is in good position for a tackle but the ball carrier jukes him out of his shoes.