I have analyzed draft for 3 seasons now. I only take 18yo's. Scout them all and then gather the info from the managers. I have been collecting info in a form of SS10+st+ft. You can't actually see defence in the box score. I still think I don't have enough info, but I do change their performances to 48 minutes (with different constants depending on their minutes in the box score) and then calculate their +-.
Atleast my own drafted players are not exactly what the box score suggested them to be. Some info seems legit, some is misleading to say the least...