[endgame]

FWIW,

1.51 Batter Aging
.651 Batter Development
1.31 Pitcher Aging
.711 Pitcher Development

Keep in mind however, and I'm not statistical guru, that these impact the growth of the players in your league created with your specific player-creation modifiers. So if you are in a position where your youngsters, like mine, are rarely created with exceptional star quality, obviously their careers may be limited and those with higher end ratings and/or performances- whether amateur or existing -will tend to have longer careers.