I disagree that teams "figured out" RG3, his knee injury has sapped his mobility and ruined his mechanics. He looks slow and doesn't have the same zip that he used to have. He also doesn't have the pocket presence needed to function without his mobility.
Kaep still has a cannon, and the speed, but is woefully inaccurate. He'll make some plays with his legs, and help out your ground game with read option.. but it's very hard to trust him to throw accurate passes - especially deep. For this reason, he's figured out because you can just stack the box against him and dare him to throw a deep ball.