gilgamesh wrote: ↑05 May 2018, 20:08
oogiebe wrote: ↑05 May 2018, 19:45
So BoxRec changes the HW rankings AFTER today's Bellow (made me look bad) ko of Haye. It snuck in as I had viewed earlier today.
Haye gets inserted into #15
Bellew gets inserted into #4.
Nonsense for both.
I don't know how the rankings are compiled, but frankly Boxrec's rankings have always been a joke.
It's a record data base. It's not even one of the 10th most reliable authorities on rankings.
all these ratings evaluate every day all bouts in the database in chronological sequence. A higher rated boxer should be expected to defeat a lower rated boxer with increasing probability by increasing rating difference.
Current Ratings
Every boxer gets a first rating of 0 before his first bout.
After every bout, the ratings of the two boxers involved are changed depending on the bout's official result (KO, TKO, RTD, UD, PTS, NWS, MD, SD, DQ, TD, DRAW).
The value of a result varies between v=1 and v=0.
The clear decision factor varies between cd=1 and cd=0.
The winner cannot lose points for KO, TKO, RTD, DQ, TD and decisions on points with cd=1
KO, TKO, RTD are rewarded with full value v=1, cd=1.
NWS is rewarded with full value v=1 for 12 rounds boxed and more and a lower value related to the number of rounds boxed. Clear decision factor cd=1.
UD, PTS, DQ, TD are rewarded with full value v=1 for 12 rounds boxed and more and a lower value related to the number of rounds boxed, clear decision factor cd=1. If the score cards are available, it may be less.
MD, SD are rewarded with full value v=1 for 12 rounds boxed and more and a lower value related to the number of rounds boxed. Clear decision factor is limited to cd=0.5. If the score cards are available cd may be less.
DRAW is rewarded with full value v=1 for 12 rounds boxed and more and a lower value related to the number of rounds boxed. Clear decision factor cd=0.
If the score cards are available, the value rewarded is in direct proportion to the rounds boxed, with full value v=1 for 12 rounds boxed and more. The clear decision factor is in proportion to rounds boxed and the mean score difference per judge. cd=1 for a mean score difference per judge of 50% of the rounds boxed.
All bouts are regarded to have the same weight independent of titles.
The winner gets a certain part of the opponent's points and a certain part of the rating difference to the opponent's rating.
For a DRAW the rating of the higher rated boxer is reduced by some part of the point difference; the rating of the lower rated boxer is enhanced by the same amount of points.
The full relative point reward is 33%. It is in direct proportion to the pre-bout rating of the defeated opponent.
The winner also gets additional points from the bout's additional points value in proportion of the opponent's rating to his own rating. The proportion is (r_b+10) / (r_a+r_b+20), where r_a is the pre-bout rating of the winner and r_b is the pre-bout rating of the loser.
The bout's additional points value comprehends 3 parts
1 point anyway - another 4 points for an opponent connected by strong results to other connected boxers - and another up to 250 points multiplied by bout value v and clear decision factor cd for an opponent in the division top 50 for men and the division top 30 for women
The rating of a boxer is reduced, if he didn't box an opponent with a rating of at least 50% (for men) or 33% (for women) of his own rating points within 18 months.
The rating of a boxer is reduced by up to 50% in proportion to the difference of 2 times the rating points of his best opponent in this time period minus his own rating for men.
The rating of a boxer is reduced by up to 50% in proportion to the difference of 3 times the rating points of his best opponent in this time period minus his own rating for women.
The reduction is in proportion to the time the requirement was missed.
The rating of a boxer is reduced by 50% for every time period of inactivity of 18 months.
The pre-bout rating of a successfully debuting boxer is set to 25% of his opponents pre-bout rating.
The rating points are in relation to a weight division. The rating points are converted with the cube of the upper weight limit ratio of the old and new weight division.
The winner is always rated higher than the loser. the minimum margin is: mean pre-bout ratings of both r_m = (r_a + r_b)/2; r_new_winner = r_m + earn_f*v*cd/4; r_new_loser= r_m - earn_f*v*cd/4
Formula
If a boxer with a rating of r_a before the fight defeats a boxer b with a rating of r_b before the fight with result of value v and clear decision factor cd, the new ratings r_a_new and r_b_new after a fight are, earn_f is 33.3%:
earn = earn_f * v * (r_b*cd + (r_b-r_a)/(1+2*cd));
r_a_new = r_a + earn
r_b_new = r_b - earn
Additional points:
opponent is connected or not: con=(1 or 0), value of result v, clearness of decision cd, winner's rating r_a, opponents rating r_b, opponent's rank in division rank (#1 is equivalent to #2):
additional points winner = (1 + 4*con + 250/(rank-1) * v * cd) * (r_b+10)/(r_a+r_b+20)
Rating reduction caused by missing opponent quality:
r_red-10 = (r_old-10) * (1 - 0.5*(1 - 2*best_opp/r_old)) for men
r_red-10 = (r_old-10) * (1 - 0.5*(1 - 3*best_opp/r_old)) for women
Examples
Boxer a UD 6 boxer b, scores 59:55 58:56 58:56, a has 1000 points, b has 500 points, opponent's rank outside top 50 and he is not connected
A 6 rounder is rewarded with value 6/12, v=0.5
UD is rewarded with cd=1 at maximum
mean score difference per judge is (4+2+2)/3 = 2.667, which is rewarded in direct proportion to half the rounds boxed with cd= 2.667/3 = 0.89 at maximum
so cd=0.89
earn= 0.33 * 0.5 * (500*0.89 + (500-1000)/(1+2*0.89)) = 44
r_a_new = 1000 + 44 = 1044
r_b_new = 500 - 44 = 456
additional points:
additional points winner = (1 +4*0)* (500+10)/(500+1000+20) = 0
r_a_new = 1044 + 0 = 1044
r_b_new = 456 + 0 = 456
Boxer a SD 4 boxer b, scores 39:37 39:37 37:39, a has 1000 points, b has 500 points, opponent's rank outside top 50, but he is connected
A 4 rounder is rewarded with 4/12, v=0.333
SD is rewarded with cd=0.5 at maximum
mean score difference per judge is (2+2-2)/3 = 0.667, which is rewarded in direct proportion to half the rounds boxed 0.667/2 at maximum\
so cd=0.333
earn= 0.33 * 0.33 * (500*0.33 + (500-1000)/(1+2*0.33)) = -15
r_a_new = 1000 - 15 = 985
r_b_new = 500 + 15 = 515
additional points:
additional points winner = (1 +4*1)* (500+10)/(500+1000+20) = 2
r_a_new = 985 + 2 = 987
r_b_new = 515 + 0 = 515
More complex - Boxer a KO 4 boxer b, a has 300 points, b has 400 points, boxer b is connected con=1, v=1, cd=1, opponent's rank in division rank=5
earn= 0.33 * 1 * (400*1 + (400-300)/(1+2*1)) = 143
r_a_new = 300 + 143 = 443
r_b_new = 400 - 143 = 257
additional points:
additional points winner = (1 +4*1 + 250/(5-1) * 1 * 1)* (400+10)/(400+300+20) = 38
r_a_new = 443 + 38 = 481
r_b_new = 257 + 0 = 257
