Added ATTQOTD: Okay, I went through and added places to my spreadsheet.
Absolute best placement, 100th out of 178 (Down By The Bay 5k, 2015)
Absolute best placement by age group, 11th of 11 (Hellyer 10k, 2017)
Relative best placement, 3865th out of 11548 (Star Wars Rival Run 10k, 2019)
Relative best placement by age group, 356th out of 814 (Star Wars Rival Run 10k, 2019)
Absolute worst placement, 11229th out of 16316 (Star Wars Dark Side Half, 2017)
Absolute worst placement by age group, 761st out of 964 (Star Wars Dark Side Half, 2017)
Relative worst placement, 251th out of 264 (Brazen New Year's Day 10k, 2018)
Relative worst placement by age group, 2-way tie: 11th of 11 (Hellyer 10k, 2017) and 18th of 18 (Brazen New Year's Day 10k, 2018)
What this is telling me: I was poorly trained in early 2017. The Brazen NYE 10k is evil. And I'm in much better running condition now than I was - my relative best placements were both last month.