Online and live games are vastly different. Just because you "perfect" your online game does not mean you have "perfected" your live game.
Example:
Online players get to play four, five, six, up to eight or more cash game tables at one time. They become used to seeing literally hundreds of hands in a hour. When they play live they only get to see thirty or forty a hour. This causes many to start to play hands they would not when they are online or try to make moves they would not make online. So, they may have their online game "perfected" but it does not transfer over to the live game because they are out of their element. If you want to "perfect" your online game stick to playing online, conversing with online players who are better than you about hands, and studying how to get better online. If you want to play live, then follow the same above process, but talk to players better than you that also play live, study books and forums that talk about live poker, and work on "perfecting" your live game in a casino.