Guide to the 2015 Group Draw

Riot·9/10/2015, 10:57:59 PM·2 votes·32,566 views

A procedural guide to the Group Draw.

In the 2015 World Championship format announcement, we shared some details on how the 2015 Group Draw works. In this article, we’ll be going into greater detail on how the groups are drawn from a procedural standpoint. In the Group Draw Show this Saturday, September 12, at 1 PM PDT, we’ll be holding the draw according to the rules and structure described below.

The info in this post is pretty dense and technical. It’s designed to give you a solid understanding of the mechanics of the draw process and a clear idea of what to expect during the live draw.

Group Draw Structure

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Group Draw Rules

No group can have more than one team from the same region. So, for example, CN #1 and CN #2 cannot inhabit the same group.
Each group must have exactly one team from Pool 1
Each group must have exactly two teams from Pool 2
Each group must have exactly one team from Pool 3

Procedure

The draw begins with the seeds physically separated into three bowls by Pool. The groups are arranged in alphabetical order from left to right - A, B, C, and D. First, all of the seeds from Pool 1 are drawn randomly, then Pool 2, and finally Pool 3.

When a seed is drawn, it is placed into the next group available in alphabetical order so long as that would not render the draw invalid at any future point by preventing another seed from being placed in a valid spot. For example, if placing the next drawn seed into Group A would make it impossible to place a future seed without violating a rule, that seed would need to “skip” Group A and be placed in B, C, or D, depending on what spot is available - more on this later.

In Pool 2, each group must have one Pool 2 seed before any group has two Pool 2 seeds, unless doing so would create an invalid draw.

For example, imagine #2 CN has just been drawn as the first team from Pool 2, but #1 CN already occupies Group A. Because of rule #1 (no group can have more than one team from the same region), #2 CN cannot occupy Group A, and is placed in the next available group, Group B, which currently has space for Pool 2 teams and has no CN seeds.

Invalid Draws

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Because seeds are drawn randomly and there are several rules governing where those seeds can go, there are a few situations we can run into in which a draw cannot be completed, rendering the draw “invalid”.

In the above example, #3 KR has nowhere it can go because:

Group A already has two Pool 2 seeds
Group B already has two Pool 2 seeds
Group C already has a seed from KR
Group D already has a seed from KR

#3 CN is in a similar dilemma:

Group A already has two Pool 2 seeds
Group B already has two Pool 2 seeds
Group C already has a seed from CN
Group D already has a seed from CN

There are two ways to deal with situations like this. One would be to simply restart the draft until we avoid an invalid draw, but this could result in an infinite number of restarts and, since the show is live, isn’t realistic. Alternatively, we could monitor the draw as it proceeds, and use a series of logical checks to identify when placement of a specific team would create an invalid draw down the road. If that happens (specifically before picks 9, 10, 11, 13, 14, and 15), we can move the team to the first available placement that would avoid the invalid draw.

To see an example of how one such check would work, let’s revisit the invalid draw example pictured above. In that example, we’re already at a point where the draw cannot be resolved. The problem arose when #2 EU was drawn - when #2 EU was placed into Group A (despite satisfying Rule #1), that left two teams (#3 KR and #3 CN) who could only fit into one spot - the third slot in Group B.

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However, if we rewind to before Pick 9 (when #2 EU was drawn), we can see that it’s possible to anticipate and prevent this by placing #2 EU in a spot that would not create an invalid draw further along in the draft. What follows is the logic for deducing where #2 EU must go when drawn at Pick 9.

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In this example, exactly 1 KR and 1 CN team remain, and two of the four groups have both KR and CN teams. To avoid putting ourselves in an invalid draw, if the 9th overall pick is not a KR or CN team, it must be drawn into the next available group that contains both a KR and CN team. This means if we draw #2 EU next, it must go to Group C:

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If we had instead drawn #3 KR or #3 CN, that team would be placed in Group A. These kinds of checks ensure that the draw can proceed without the need to restart and will stay in compliance with the rules of the draw.

Conclusion