From MLB Power Pros Wiki

Two Types of Stats, Two Modes of Practice

Boost Stat

A stat you must pay the bulk of upgrade cost to boost. Often on a 255 scale.

Gamble Stat

A stat easily boosted by gambling. Often on a 7 or 15 scale.

• For the most part, the total amount of exp points determines how far Boost Stats can be upgraded.
• Gamble Stats, on the other hand, are controlled by the number of times gambled.
• Boost Stats are affected by Baseball Sense more so than Gamble Stats.

Examples

Fielders:

• Boost Stats - Power
• Gamble Stats - Contact, Trajectory, Run Speed, Arm Strength, Fielding

Pitchers:

• Boost Stats - Stamina, Control
• Gamble Stats - Top Speed, Breaking Ball levels

Boost Practice

Practicing with the intent of spending the bulk of exp points gained on a Boost Stat.

• The amount of points is what matters. You get what you train and pay for.
• Thus practice efficiency is measured in: Points Gained/Turn
• If you skip practice, there aren't many ways to make up for it (compare with Gamble Practice below).

Examples

• Weight Training and Hyper Recovery
• Target Practice Chain (Often done at the end of a pitcher's Third Year)

Gamble Practice

Practicing with the intent of gambling on the next turn.

• The types, not amounts, of the exp points are what matter the most. Using combos, it's possible to gamble more than once per turn.
• Thus efficiency is measured in: Gambles/Turn
• Gamble Practice can/should be skipped when there is an exp point gain that enables gambling after the turn. Eg. Before games. From the perspective of boosting Gamble Stats, a Gamble Practice on the turn before the game is a complete waste.
• Thus by using these turns to date or work the player can minimize the damage of spending a turn not practicing. A Boost Practice on these turns is also a good option so long as it doesn't break up a Tech Practice chain.

Examples

• Pitchers: Shadow Pitching Run; Shadow Pitching -> Gamble on both Top Speed and a Breaking Ball level on next turn (Requires a stockpile of Mentality points)
• Fielders: Batting Practice -> Gamble on both ARM and FLD on next turn (Requires a stockpile of Quickness points)