User blog comment:ClariS/Unofficial PBE Patch Notes (148)/@comment-4431813-20120915115339/@comment-4743916-20120916165104

The thing is lategame dueling is almost never the case as teamfights rule the game and everyone is extremely grouped up. Considering how Vayne specializes in dueling which is a early and mid-game situation, she's not that strong lategame since her mobility is somewhat bound to wherever her team is, making most of her chasing potential unused.