KO match draw after Round Robin group stage

[dschingis27]

Hi there, I recently discovered that round robin group stage results do matter for the matchmaking in the subsequent KO round. Is that true? It appears in a tournament where 2 players per group qualify for the KO stage, the group winners are seeded and paired against the 2nd places from the groups. The best group winner plays against the worst 2nd place (best/worst in terms of Elo), the 2nd-best group winner against the 2nd-worst 2nd place, and so on.

Here is an example: https://boardgamearena.com/tournament?id=432617 I am the highest-rated Elo player, but I only made 2nd place in the group stage. So instead of being matched against the lowest Elo player, I was matched against the lowest Elo-rated 1st place (because I am the highest rated 2nd place). All the pairings are 1st place against 2nd place. I am not complaining, it makes sense.

Until today, I was under the impression that when a KO stage starts after a group stage, the KO stage is treated as a usual completely new KO tournament, with seeding based only on Elo, no matter the group stage results. I was positively surprised that I was apparently wrong.

Now my question: Has it always been like this? Or is it a recent update? I was just super surprised today to find it out.

[dschingis27]

If this seeding really works that way, one could also think about some "complex" KO qualification shenanigans similar to current UEFA Champions League. So e.g. in my example above, I had 8 groups with 5 players, the best 2 made it to the KO stage that starts with round of 16. If I had set 3 players per group to qualify for KO, then 24 players would make it to the KO stage. I would assume that the 8 group winners were seeded into round of 16 while the 16 (2nd places + 3rd places) play one in-between KO round to find the 8 opponents for the 8 group winners for the round of 16.

I am not sure if it works like this, but it would great. It can put some spice into round robin groups.

[BananaHarambe]

Hi, I can confirm that second stage in group stage tournaments are seeded. I use that to my advantage with this setup https://boardgamearena.com/tournament?id=417621

2 group Swiss with 7 advancing going into single elimination. The 1st place players always receive a bye as expected and the full bracket follows proper seeding based on placement. Since there are 2 groups with same placement it will randomly pair the different groups together. It will not prefer to match cross-group or same-group in second stage, just totally random.

In my format I am expecting a full 64/64 tournament with 32 per group, 5 rounds Swiss to fully sort players. Expected outcome
1 5-0
5 4-1
10 3-2

Having 7 players qualified means that anyone with 4-1 or better advanced so it is a “double elimination” tournament. The 5-0 gets rewarded with a bye and better bracket.

There is 1 extra spot to account for a 3.5 3.5 outcome when there was a tie between two top players. Usually one 3-2 with the highest tiebreaker advances and that’s okay. The 3-2 will have the bottom seed so they will have the toughest bracket, getting paired against 2nd immediately I believe.

I highly this format for “double elimination “ style tournament.

[dschingis27]

Thank you for the reply and your interesting example! This is great. My head is already spinning around new interesting tournament formats.

Of note though, this system doesn't go completely without problems or awkward situations. In my own example above, my opponent was paired in KO against me, the highest-rated player in the tournament, exactly because they won against me in the round robin group stage and achieved 1st place in our group. Because of that, they became worst-rated 1st place, to be matched against best-rated 2nd place (=me). Also if they win their KO against me, they are paired against the best-rated 1st place in the next round. Had they just lost their round robin game against me to become 2nd place in our group, they would have been a medium-rated 2nd place to be matched against a medium-rated 1st place, and less strong opponents in subsequent rounds.

So in a way, my opponent was not at all rewarded for becoming 1st place in our group, or they are even incentivized to go for 2nd place. I don't know how to solve this but it's an awkward side effect of the current system.
Probably a better system would be a random pairing of 1st places against 2nd places rather than seeded by Elo rating.

Now that I think about, we have this situation also in many real-life championships, a 1st place in a round robin group does not guarantee to avoid the toughest opponents in subseqent rounds if said tough opponents underperform in their groups. (E.g. think of Paris St.Germain in last season's UEFA Champions League or I can think of several Basketball championships.)

[BananaHarambe]

Thank you for the reply and your interesting example! This is great. My head is already spinning around new interesting tournament formats.

Of note though, this system doesn't go completely without problems or awkward situations. In my own example above, my opponent was paired in KO against me, the highest-rated player in the tournament, exactly because they won against me in the round robin group stage and achieved 1st place in our group. Because of that, they became worst-rated 1st place, to be matched against best-rated 2nd place (=me). Also if they win their KO against me, they are paired against the best-rated 1st place in the next round. Had they just lost their round robin game against me to become 2nd place in our group, they would have been a medium-rated 2nd place to be matched against a medium-rated 1st place, and less strong opponents in subsequent rounds.

So in a way, my opponent was not at all rewarded for becoming 1st place in our group, or they are even incentivized to go for 2nd place. I don't know how to solve this but it's an awkward side effect of the current system.
Probably a better system would be a random pairing of 1st places against 2nd places rather than seeded by Elo rating.

Now that I think about, we have this situation also in many real-life championships, a 1st place in a round robin group does not guarantee to avoid the toughest opponents in subseqent rounds if said tough opponents underperform in their groups. (E.g. think of Paris St.Germain in last season's UEFA Champions League or I can think of several Basketball championships.)

Hi, I looked closer at your linked tournament. Everything is working as expected, but I agree that same group rematch in the first SE game is not ideal. In your case it was based off the 1st and 2nd placements and randomly assigned. You just got unlucky with the re-pairing. Player ELO should not affect the pairing. It appears to be completely random.

[BananaHarambe]

Actually, you might be onto something about ELO having an effect. See this one https://boardgamearena.com/tournament?id=427733

Your idea of the highest Elo 2nd pairing with the lowest 8th in my setup and so forth occurred for all pairings based on what I observed. More evidence is needed and it is worth observing more to confirm.

[Mathew5000]

Until today, I was under the impression that when a KO stage starts after a group stage, the KO stage is treated as a usual completely new KO tournament, with seeding based only on Elo, no matter the group stage results. I was positively surprised that I was apparently wrong.

Now my question: Has it always been like this? Or is it a recent update? I was just super surprised today to find it out.

I believe this exact issue was raised in 2021 in this thread: https://boardgamearena.com/forum/viewto ... 4&start=20 at the top of page 3, the two posts by Sprockitz:

• viewtopic.php?p=89480#p89480

• viewtopic.php?p=89610#p89610