I kind of did this for a 12 man league. This is what I did:
1. ranked each team 1 through 12 according to total points scored over the history of the league (assign 12 pts for #1 rank, 11 for #2 rank...)
2. ranked each team according to their average season points rank. ie, if Team A finished 3rd, 6th and 12th in total points over a 3 year span, his average points rank would be (3+6+12)/3 = 7 ; assign 12 pts to highest avg rank, 11 pts to second highest and so on
3. combined the above two points assigned to create an overall ranking
The reason #2 is important is so that numbers don't get scewed if one guys does amazing in 1 season and blows everyone away and then does poor other years. This year would be a good example. Anyone who drafted Brady and say Moss might easily outscore everyone by 100-300 points+ depending on your scoring system. Add that to 2 bad season for points and he will still likely be the top ranked fantasy player if you only use #1 above. This happened in my league - the guy who was #1 in total points scored finished #1, 8 and 10 in points during the 3 years being used. There is no way he is the top fantasy performer and that is why I added in #2
Other things you could use:
- season finish (ie, planing for playoffs and success in playoffs is important). I didn't take this into account because of lack of info and laziness)
- season record - I like points scored as a much better indicator though to take out the luck, bad luck in match-ups factor
- total money won - might be good for leagues with weekly payouts etc as with money leagues, the true measure of success is money won... right?