Here you go, it won't make most people here very happy...... "In the past few seasons, hitters no longer improve once they arrive in the majors. Instead, their performance is constant until they begin to decline, which, on average, is at 26 years old. Improved training and development is probably behind the shift. If fans are hoping for a young position player’s performance to peak, they might be sorely disappointed. Chances are the player is likely producing at his career-best already." http://www.fangraphs.com/blogs/hitters-no-longer-peak-only-decline/ Remember, this is what to expect to happen, not will for each player. And, a team should plan on what they expect to happen......