Practice 2008
From MLB Power Pros Wiki
In Success Mode 2008, there are 5 practices for both fielders and pitchers.
Fielder: Weight (Strength) Batting (Strength and Technique) Run Speed (Quickness) Fielding (Technique and Quickness) Arm Strength (Strength and Technique)
Pitcher: Weight (Strength) Top Speed (Strength and Technique) Accuracy (Technique) Fielding (Technique and Quickness) Breaking Ball (Breaking Ball)
Keep in mind that all of these practices increase mentality, but only slightly (single digits)