The biggest thing I've seen at the local level is tons of guys doing speed/quickness training....sprints, plyometrics etc with no real strength training. Taking a young athlete that is weak and not very explosive and doing explosive speed exercises without developing base strength is silly.
Look at Olympic sprinters. Those guys spend a lot of time under the bar. There is a reason for that.
Regardless of sport, take a young athlete and squat, deadlift, bench, overhead press, pull ups as a base and you will see improvements in performance. That is basic training that is largely ignored because it takes time, focus, effort and willing participants to progress correctly.
At the highest levels it's mostly (I assume) going to be technique work and specific things to shave tenth of seconds off of a timed sprint.
Things like diet, nutrition, weight, sleep....all of those things before a timed run could be the difference between a 4.52 and a 4.41. Tiny things and "huge" differences in that world.
I have a friend who plays tennis. Pretty decent amateur player. Wins tournaments etc.
He has been working on getting his serve speed up.
Worked with a tennis coach, started running (although not sprinting) and doing some other things without much difference.
I got him (finally) to do a few of the things I would do with pitchers. The rotational movements (through the hips) of a tennis serve, baseball pitch, golf swing are all very similar.....hip shoulder separation. Got him to squat, deadlift (but mostly squat), overhead press and throw medicine balls in specific ways....bam, his serve speed jumped over 10% in short order.
So, for him, going to a speed coach or even a technique coach didn't offer much. He was in good cardio shape with good technique. But, he was weak with some shoulder issues (over head press helped with this).
Anyway, this stuff is interesting, but I'm not sure how squeezing another tenth of a second out of a forty time is going to help a guy who is already fast in a sport where you rarely run in a straight line. Doing other stuff to impact change of direction and explosiveness could benefit for sure.
But, it obviously works for CM.