What can you learn from the world's most successful investors?

If it's possible to learn from the world's most successful investors, then why can't they teach their successors?

From 1977 to 1990, Peter Lynch, famed investor and manager of the Magellan Fund, returned 29% annually versus the S&P 500 with a 15.5% annual return. 

In the last 10 years, Magellan had a 7.2% annual return versus the S&P of 8.6% annually, under-performing by 1.6%. 

Since Peter Lynch left Magellan, he has been the Vice Chairman of Fidelity, having the time, opportunity, responsibility and incentive to insure relative performance was maintained. If his successors couldn't learn from Lynch, what chance does the individual investor have?