How good is good for an incoming HS freshman?

With real training you could hope for 4:40 or better for 1600, and ballpark 2:05 for 800 next year from him. As for cross country it's tough to guess. He probably wouldn't be running sub-16 as a freshman considering he'd have to run around his 1600 PR 3 times... but he certainly has potential.

Ok, thanks! Is 16:30ish in the realm of possibility?

In the future absolutely, but it's hard to say for this year. He could adapt extremely well to a structured training program get really fast really soon, but it really depends how well his body responds to the training. Sure it could happen.

5:05 at that age is probably equivalent to 17:30-18. You can probably drop 30-45 seconds per year in cross country to get down to 15-15:30 as a senior or college freshman. Then again, some people improve very little in high school.

Hey dad, I'm gonna be fine next year. Please stop asking message boards how fast I'm gonna be.

one of my friends just completed his freshman year. he ran 5:30's in 8th grade for 1600 and broke into the low 17s for xc. The kid will probably do really well

OP: As an 8th grader I ran slightly faster than that in the 400 and 800 but slightly slower in the 1600 off of playing soccer and no track training. I ran 1830s my freshman year of xc, then ran 4:49 in track.

My friend ran significantly slower than those times in 8th grade, then ran in the low 17s in xc his freshman year and 4:35 in track.

The point is you can't predict too much based on "no training" times how somebody will then do once trained, other than to say they should at least get a little faster, but they may get way faster. I don't think myself or my friend were outliers in any way. The kid you are talking about could run 19 minutes in xc as a freshman, or he could run 16:00s. Most likely he will be somewhere in the middle, in the 18:00 range, but that is making a guess based on very limited info.

Don't set expectations too early. Look at how he is doing after 3-4 months of training compared to known quantities (your returning runners that he is working out with) and start to set conservative goals based on that, then modify them if he exceeds them. This will ensure he stays interested and starts with the attitude of "hard work in the long term will get me the results I want."

Those were very close to my times in 8th grade (mileage was in 15-20 miles/week range during XC and track).

I ran the following my freshman year:

2:06 800

4:40 1600

17:08 XC 5k

It all depends on when the puberty hits. I know someone who was slightly faster than those PRs coming out of 8th grade. 7th to 8th grade was a huge jump. But 8th grade to freshman year was an even bigger one. They ended up around 53s, 2:00, 4:35, 16:00 (xc). It really depends on the combination of talent (also accounting for puberty), hard work, and smart coaching.