From MLB Power Pros Wiki

Description

Secrets of Hitting is an item in Success Mode 2007 and 2008. It will appear as a red book icon on the inventory screen, and can be used to acquire a random hitting ability.

The book is not sold at Bison's Shop but can be found inside a Surprise Bag, or obtained from various events.

Possible Abilities

Secrets of Hitting can potentially give any blue hitting ability except Clutch Hit, Vs Lefty, Intimidator, Power Hitter and Contact Hitter.

In addition to blue abilities, it can also give the neutral ability Pull Hitter.

Baseball Books
Secrets of Hitting | Secrets of Defense | Secrets of Pitching | Legends of Baseball