He's right, that is pretty mediocre actually, even at 15. I was close to cracking into the 4 minute miles in middle school, 8th grade - like 4:59 I'm talking, but never quite got there. A few seconds off. I ran cross country in high school, quit my sophomore year, but at that point, I was averaging a mile pace of about 5:29 or so. I ran the 3.1 mile right around the 16:40's on a consistent basis.