or anything other than an officially set-up laser test are going to vary wildly.

And when you have situations where people are being hand-timed on different days under different situations, you really aren't going to get a good picture of who the fastest guy really is... or if a guy is even faster or slower than last year (unless it's a dramatic jump one way or the other).

40 times give you a general idea of the speed vicinity someone is in, but 95%+ of the time they are a joke as far as being a precise and accurate measure of real speed or relative speed compared to someone else.

A couple of years ago I was at an event where 40 times were officially clocked and there were at least ten guys in attendance that supposedly had sub-4.4 speed and two with supposedly sub 4.3 speed. The fastest any of these guys ran was in the high 4.4s, most were in the low 4.5s.

They could have gotten a raw deal on the setup, but it was official and within official standards. The start setup and the running surface may have been "slow" or something they weren't used to. Who knows. Certainly humidity, temperature, and altitude can mess with elite sprinters.

People just need to know football athletes are seldom really as fast as the 40 times that are posted -- don't put too much into them, and certainly they aren't definitive about who's faster on a team. Usually the guys on the team know who's faster and it doesn't take a clock to know it.