.....If you can tell a kid what hes doing wrong when running and he gets faster then... Cant you coach speed? The object would be to make them faster, correct? If you couldnt coach speed then Butch Reynolds wouldnt have a job.
You can teach or coach techniques and knowledge of the game but some kids have a natural ability to anticipate and react quicker than others which is also a kind of "Game" speed. Some have the ability to run better routes than others. Some of the games greatest receivers had average speed according to 40 times. I would want the intangibles in a player who happens to have a little slower 40. I'm not saying you can get by without speed but speed is only part of the game. When the game is on the line I would want a player who reads, reacts, anticipates, better so they are the best position to make a play. Baseball fielders who know how to shift their weight in anticipation of where the pitch is located is another example. To me the 40 time and the 90 mph fastball are both overrated. Location and changing speeds is much more important in baseball.
But the reason coaches and scouts drool over fast 40 times and 90 mph fastballs is that they can teach a pitcher proper mechanics, and they make a fast player stronger and more disiplined. However, a team full of hard-nosed, hard-working players will most of the time beat team full of undisiplined, but more talented team.
Speed is an intangible you cant coach. You can improve speed, but you can coach it. Its just like heart. You can give pep talks and get get a kid fired up, but that will only last a few plays. Its his heart that keeps him going after that. Speed is the same thing. No matter how much you work with a guy you wont be able to move past his God given speed. You might be able to coach him on how to properly utilize all the speed he has availible, but you cannot move beyond that talent.