For position players range, glove, arm strength, arm accuracy, contact, power, vL, vR, eye, possibly pull, health, makeup, speed, base running. And you need to account for pitch calling to include catchers, and keep in mind other ratings affect development so also have some value. For pitchers durability, stamina, health, makeup, control, vL, vR, velocity, gb/fb, P1, P2, P3, P4, P5.