Well, the "sophomore slump" isn't so much a curse as it is a simple explanation for teams around the league "getting tape" on a young player and thus exploiting the weaknesses they see. If you noticed last year Bekcham was getting a ton of low-and-in fastballs, and he was crushing them into the left field gap for easy singles and doubles. Now, he's lucky to see ANYTHING in that zone he likes, much less a grooved fastball.
I am also convinced that there is a minor flaw in his hitting mechanics this year, though I can't put my finger on it.