Power is, quite simply, how far a player can hit the ball. Each batter in RBI has a power rating stored in the game's ROM. The higher the rating is, the farther the player can hit the ball. Rafael Santana, with 708, has the worst power rating for position players, despite being a starter. The highest power rating belongs to Andre Dawson with a 954. All pitchers have a 640 power rating. Theoretically, the power rating may go anywhere from 0 to 65,535.
The power rating has, without a doubt, been proven to be the most important statistic for RBI players. Though speed and contact have their importance, by and large a batter's power rating determines how good they are.
Pinch Hit Power Boost
By watching the RAM of the game via an emulator, it has been discovered that all pinch hitters get a boost of 64 power points (40 hex) during their first AB. That is a big boost and explains why some pinch hitters (Joel Youngblood comes to mind) completely suck after their first at-bat...
To put that number in perspective, 64 power points is the difference between Bob Boone and Jim Rice. Or Doug DeCinces and Reggie Jackson. Or Keith Hernandez and Darryl Strawberry.