Track speed is an overrated concept when it comes to receiving. Arguably the best NFL receiver until Jerry Rice came along (who also wasn’t a burner) barely ran a sub-4.7. Yet go back to quotes from DB’s of the time period and they all say that Steve Largent was uncoverable.
If you want to say that Whittmore, Davis and Simmons are faster than Singer, I’ll take that as fact since I’m not going to look up 40 times. But football is so much more than straight line speed. Which is why I talked about functional speed and the willingness to scheme that speed to maximum advantage.