cross country courses can't be trusted. those 10k times do not indicate sub 17 ability. the 800 workout, if measured on a track, is solid but doesn't indicate too much. When I ran 8x800 on, I think, 45 seconds rest at altitude, under control at 2:32-33, I ran 16:04 at the end of the week at sea level and could have run faster if I was more aggressive. At 2:39, with normal endurance, you'd figure to be able to run high 16s but you have considerably worse endurance, as is common with younger athletes, and so figure to run a legitimate course in mid to high 17.