Tenax
Joined: Jun 09, 2022
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Feb 14, 2023 - 12:13 |
 
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I became very passionate about the mathematical aspects of the new ranking system. It is quite clear to me how the new mechanism works as quite well explained by Christer here https://fumbbl.com/p/blog&c=Christer&id=24402, here https://fumbbl.com/note/christer/CR and also in other forum, but I am left with a doubt about decay.
In particular I refer to the last line of this explanatory note
https://fumbbl.com/note/christer/CR
To add an element of rating decay, the rating used to compare and rank coaches is based on both the direct rating r' and the rating deviation RD' as follows:
CR = r' - 2 * Max(RD' - 75, 0)
Here the implicit assumption is that CR is re-calculated only if a coach plays a competitive match, right?
If I decide (just an extreme example) after reaching a certain Coach Rating level (let's say 1700) not to play any more any competitive matches but, for instance, only league matches, does my CR decay or stay constant over time?
Thank you all for any clarifications |
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koadah
Joined: Mar 30, 2005
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Feb 14, 2023 - 12:35 |
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MattDakka
Joined: Oct 09, 2007
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Feb 14, 2023 - 12:36 |
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Also, if is it possible to know (it's a related question): do the specific racial rankings decay?
I managed to be top 1 with some races and my CR is still the same for those particular races, even if I have not been playing them for way more than 2 days (I expected to lose some CR points after a while).
Only the All Rosters CR seems to decay, but not the CR for each specific race.
I'm quite sure of this because I use to check the top 1 for the races I play and I noticed that.
A possible explanation could be that specific race CR has a longer decay time than 2 days, maybe 1 month or more. It doesn't seem to be 2 days. |
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Nelphine
Joined: Apr 01, 2011
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Feb 14, 2023 - 13:52 |
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I don't think so. I havrbt played a c match since my first round WO game, and I still have the same CR as after that game. |
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Sp00keh
Joined: Dec 06, 2011
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Feb 14, 2023 - 14:00 |
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I've not played a [C] game in more than 2 weeks, my CR has stayed the same, and my rank has gone up  |
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koadah
Joined: Mar 30, 2005
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Feb 14, 2023 - 14:02 |
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Nelphine
Joined: Apr 01, 2011
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Feb 14, 2023 - 14:51 |
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i admit i thought that your actual rating wouldn't change, but the visual would keep displaying as your variance decayed, so that it would keep going down for a while |
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DaCoach
Joined: Jul 22, 2004
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Feb 14, 2023 - 15:24 |
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| Sp00keh wrote: | | I've not played a [C] game in more than 2 weeks, my CR has stayed the same, and my rank has gone up |
Looks like it will decay any day now.
You're at RD 75, and as soon as that increases from inactivity, your CR will drop from your base, if I read it right:
https://fumbbl.com/p/coaches?start=2 |
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Nelphine
Joined: Apr 01, 2011
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Feb 14, 2023 - 15:41 |
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ah its only been 13 days for me. |
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Tenax
Joined: Jun 09, 2022
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Feb 14, 2023 - 17:54 |
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I have the impression that there is no CR decay if you don't play any competitive matches.
Even when your RD' is greater than 75.
I did just a quick analysis by selecting some Coaches with RD' > 75 from the list https://fumbbl.com/FUMBBL.php?page=coaches and I found some not playing a competitive match since more than 1 month still keeping their CR constant. Probably they have to play at less one competitive match to have their CR' updated. |
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MattDakka
Joined: Oct 09, 2007
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Feb 14, 2023 - 18:03 |
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If you have to play to have the rank updated then decay is not that useful. |
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Rawlf
Joined: Jul 15, 2007
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Feb 14, 2023 - 18:10 |
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Tenax, can you give an example? Because evry coach on that list you linked that has a RD' over 75 has a CR which is lower than their true rating r'. And the CR is what is displayed on their about page and so on. I don't see the what's wrong? |
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commisaro
Joined: Nov 15, 2015
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Feb 14, 2023 - 18:31 |
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I like the new rating, although I do wish it took into account the races being played. There should be a way to augment Glicko2 with a variable accounting for the race each coach is playing -- you shouldn't lose as much CR when you lose playing as Halflings against Dwarves as vice versa. And without such a modification, it incentivizes playing only high-WR teams if you want to top the leaderboard. |
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Garion26
Joined: Nov 28, 2021
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Feb 14, 2023 - 20:33 |
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| commisaro wrote: | | I like the new rating, although I do wish it took into account the races being played. There should be a way to augment Glicko2 with a variable accounting for the race each coach is playing -- you shouldn't lose as much CR when you lose playing as Halflings against Dwarves as vice versa. And without such a modification, it incentivizes playing only high-WR teams if you want to top the leaderboard. |
While I understand your point - really is topping the leaderboard the point? It's an imperfect (though better then it was) measure of skill given that this is a dice game. I get it we have a vocal minority of coaches who want to max out CR. But don't the rest of us just want to get better at Blood Bowl?
Yes there are matchup specific issues - but while you could in specific issues like zons/stunties vs dwarves, you probably can't automate everything thing that causes a disadvantageous matchup (like losing your sure hands player before a game with an AG 5 strip ball player)For example pretty extensive perpetual online league data shows at low TV chaos teams aren't very good but at high TV they get better and a particularly bad matchup for teams like dwarves they lose to at low TV. Should the CR calculator do a different adjustment at TV 1000 then TV 1800?
Take it as imperfect measure of skill, heck take winning the game itself as an imperfect measure of skill. Try and make the best decisions given the constraints of the game state recognizing the dice may be unkind and let the post game data crunching fall where it may. |
Last edited by Garion26 on %b %14, %2023 - %20:%Feb; edited 1 time in total |
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Tenax
Joined: Jun 09, 2022
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Feb 14, 2023 - 20:36 |
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| Rawlf wrote: | | Tenax, can you give an example? Because evry coach on that list you linked that has a RD' over 75 has a CR which is lower than their true rating r'. And the CR is what is displayed on their about page and so on. I don't see the what's wrong? |
Yes sure:
One example just to take the first of the list who by hazard has RD 100> 75
https://fumbbl.com/p/coachdevel?c=Spartako&r=0&type=overall
https://fumbbl.com/FUMBBL.php?page=coaches
the rating is fixed since his last match played in competitive division (1st of February 2023 : rating 1878) exactly the same as indicated in the diagram.
Maybe I miss something ...? |
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