Disclaimer, I haven't dug through the hex yet. Other games store stats adjacent to player names; it doesn't seem to me Bases Loaded does.
But in the other baseball games I've looked at (Baseball Stars, RBI Baseball, Baseball Simulator), a hitter's power is usually controlled by 6 bytes. 2 bytes for Average, 2 Bytes for power and 2 bytes for accuracy. These bytes are almost always flipped, so a batting average of .302 (#$12E) is usually stored in hex as #$2E01. Power is usually much higher than average, anywhere from #$0A28 to #$04B0 (650 to 1200 decimal). The higher the values for power and average, the better the hitter.
The third value controls a batter's accuracy. If the ball isn't struck cleanly, the accuracy value is subtracted from the power value. These accuracy values usually run from #$00 to #$32 (0 to 50 in decimal).
Every game is different, but hopefully I'm flickering a flashlight into the dark abyss of this hex.
I'll also mention (since it took me so long to figure out) that most baseball games (as they're made in Japan) store pitch speed as kilometers per hour instead of miles per hour. If you have any specific questions, feel free to ask.