Started at the 2-mile point, so 1st and 2nd splits are actually the 4th and 5th miles I ran.
4th mile I had a side cramp. That's pretty unusual. Probably lost a minute trying to rest-recover that (HR in low 160's vs. ~170 on remainder.)
Did it on grass, which probably cost another minute or so.
Still had a pretty poor time - 3 minutes off PR... Maybe the grass costs more, or maybe I'm not in the shape I was in...