A quick spreadsheet conversion, some sorting, some averaging, and some chin scratching reiterated what I knew: my first 400 was more than I was ready for that day.
In seconds, my 400s were as follows:
average: 112.3, range: 21
Of 15 people, my first 400 was 10th, with two others. My second and third (awful) were a clear last. My fourth nudged up a little, to 13th, but only because I had an inordinate break.
To be fair, several of the others were coming off the Boston Marathon and other longer races. No true comparison can be made. What is helpful, as I learn what I've got, is I now know who I can run with, and who is likely just ahead of me. This will help keep me honest.
One fellow averaged 79.4 seconds per 400, running as fast as 77. The average overall was 96.6, with 88 as the fastest average for the first three (not everyone ran a complete workout, skewing the other averages toward the faster runners).
I'm itching to run tomorrow, with some trepidation. He might throw in longer repeats -- 600s and so on, which I suspect will give me some grief until I get a higher octane fuel into the engine.
I don't know what we'll be doing Thursday. Eventually, I suppose we will repeat this workout, and I'll have this as a benchmark. If for no other reason, I'll run more intelligently, learn my pace, and get a feel for time (i.e. what a 1:30 400 feels like).
Everything's ahead of me.