In a quick look on the internet, the only recent study I can find, showed that an average of sixty percent of players did worse their second year on offense, than their first. However, that study did not control for the fact that batting averages were declining across the league.... The other studies I saw said that players regress to the mean their second year, but most players regress to the mean, that's why it's the mean..... So, not surprisingly, some players play worse, some better.....