http://wiki.teamliquid.net/starcraft2/Battle.net_Leaguesy = (+/-)12 + x + z
where
"y" : the total number of points
"x" : the relative expected skill level between one player's points and the other's MMR (can be negative, calculated independently per player)
"z" : the points you get from your bonus pool
=> "x" is a value in the interval of [-12,12], positive numbers are when your opponent is favored
if the game says you are even, "x" is part of {0,1,2}
if it says your opponent is slightly favored, then "x" is part of {3,4,5,6,7}
if it says your opponent is favored, then "x" is part of {8,9,10,11,12}
(of course, if you are the slightly/favored player, then "x" is negative, which means you will lose more or win less than 12 points)
"z" will be greater than zero when
your bonus pool is >0
you are victorious