Perhaps this belongs in the "Speed" thread, but the notion that "you can't teach speed" is not false. Sure, you can tweak speed a little bit, hence the presence of a speed coach. Guys who are naturally fast can be helped to become a little faster. But in comparison to something like, say, the techniques of a given football position, speed is not something that can be picked up through practice. Guys who are great athletes but with little football-specific skill can be taught to become great football players. An example would be Antonio Gates, or heck, even Vernon Gholston (still a work in progress in that regard). But guys who are naturally slow-to-average cannot be taught to be really fast. In contrast to things which are actually learn-able, speed can only be improved marginally through practice.