I looked into this to see how valuable young players are to their team.
I've found in past research that the earlier a player debuts, the better he is. There are exceptions but speaking in generalities. I wanted to see how this played out. After six hours of data analysis, I had this. Remember, these are raw numbers based on debuts from 1990 to now. Recent hitters skew it some but not enough for me to eliminate them completely. If that bothers you, consider these conservative estimates.
I was inspired to do this because of this article by Andrew Ball. I won't go into the .31% reduction and multiplying it to assign a dollar value as he did. Please read this to get a sense as to how valuable amateur talent and prospects are.
It's interesting to see the P value spike as they debut in their early 30's thanks to Cuban and Japanese "rookies". First Baseman are slow to get to productive levels. Young third baseman do extremely well thanks to players turning into sluggers later in their career. Many of the offensive 3B end up at 1B.
There is a lot of good info here but this is just scraping the surface for my final valuation system. My goal is to have a good chart to evaluate every player in baseball. I think I am pretty close after using this information as well as other information I have compiled in the past. It will take at least one subjective value to make it work though. At this point, you will have to label a player a 4,5,6 or 7 based on below average, average, above average and star level. Once I get this done, I'm not sure what I will do with it. I may post it here or I may include it in my prospect book coming out later this year. We will see...but for now, enjoy this.