Every now and then this topic arises about speed vs. route-running. And I remind what Michael Irvin said, which is speed is overrated for the receiver position. Route-running is preferable. Of course, you have outliers like Bob Hayes and Randy Moss, but, by and large, the best receivers are not blazing fast but have superb route-running skills.
Speed can be a liability for a receiver because the faster you run, the longer it takes for you to decelerate, and defensive backs can read speed receivers better because they take too long decelerating to get into their routes. Unless, they're running a "go" route, it's easy to defend a speed receiver. That's why few - comparatively speaking - pan out.