Think of the first bracket as an "Top Ten" but extended out because ten is not enough. The second bracket is a set of releases that, for various reasons, didn't make it into the top selection. Most years there are records I buy late or reconsider, hence the last bracket.
Even though there are a couple of EPs in the “main” list, I bought enough EPs this year that commanded my attention that I felt it was worth it to call a few out. When I realized I had a set that were all the same length and made by Chicago bands, I knew I had found the right criteria for an additional bracket.
Titles are links.