People grow at different rates. It's not unusual for guys to grow a few inches and add 20+ pounds while in college, especially if hitting the weight room hard. I played linebacker on my high school team at 6'2" 220, but could not bulk up enough to do it in college, so I lost 10 pounds, gained a step of speed and played safety for my college team. Other guys were playing linebacker in college after having played safety in high school or defensive end after having been a linebacker as they gained enough size to make the jump. Hell, I came in as a linebacker and beat out a true safety for the job, but by junior year that guy was on the offensive line, he gained 4 inches and 50 pounds with a huge growth spurt.