you look to be in pretty much the same shape as me. i ran 15:40s this season, but off of 70 mpw and mostly speedwork at 5k pace more or less. never did 400s that fast but easily could have. shooting for 1:14 in a half in a couple weeks so i figure we're pretty close. my 5k was on the track.
i'll give you 16 flat +/- 10 seconds.
just keep in mind that that workout doesn't mean sh1t.
and the other dud ewas right, you had no reason to close in 62. i closed a speedworkout with a 200 sub 30 the other day, which was totally stupid. that was friday and i didnt recover until today, tuesday. (i didnt just run one sub 30 200, it was on very fatigued legs after many 400s/300s/200s.)