Waller ran a 4.5 in high school

Speed work and improving your technique especially if you haven't done that type of work before is common for the combine. Some people have done that before, like anybody who ran or runs track. Some guys focus on different things, a fast corner is going to work on strength or coverage drills, but a guy like Waller should be 100% focused on his weakness so you'd expect him to

Sprinting is a sport that's heavily dependent on technique, so to think improving is impossible is odd. Nobody in college is training for and measuring 40 times so you get a guys time from the high school camp, maybe a summer workout, and the combine. 3 data points over 4+ years isn't that many.
[Post edited by soflahokie at 03/07/2022 10:54AM]