Simple, I create a spreadsheet with the years across the top. Then down the side I will put the freshman by year. Say you look back six years; start with the 2014 freshman, put them in the 2014 column.
Then I pull up the 2015 roster and put them below the 2014 freshman in the next column (the 2015 column). As I have the 2015 roster open, I put a check mark in the 2015 column if the 2014 freshman are still on the roster (as sophomores), if not I write the word NO.
Then I repeat the same process for 2016, list the freshman, then put a check next to the 2014 freshman (now juniors) if they are still on the roster in 2016, the do the same for the 2015 freshman (now sophomores). Repeat the process through the current year.
Once I build the table going back 4-5 years I then find out how much each player players each year by looking at the stats. The stats usually give the number of games played, started and for pitchers the number of innings.
This will take about 20 minutes once you are organized. It will give you a real picture as to the “success and failure” of recruiting and what a player might expect if they choose a given school.