Rating thee top five teams is the most accurate measure of pure managing skill of all the player sets. No one is on unequal footing by gaininng false points for wins based on quantity. The normal ratings are skewed by the amount of teams you have. If you play 15 teams with a .500 record you would accrue a higher rating than a .600 manager with 5 teams b/c you would get more overall victories and playoff appearances.
So many have rightfully noted that manager ratings is purely a product of quantity. More teams you have more victories, more playoffs etc.
Here all are on an equal footing. Best of 5. Truest measure of managerial skill on TSN.