I would rather use technology that looks at how fast a player actually runs when he plays. How quick does he accelerate, change direction, react, etc. What is his top speed when creating separation or getting to the ball. I might use a 40-time to help me recruit at the college level since those tools aren't available. But at the pro level, I might not even glance at it unless it is an outlier. You might be fast, but do you play fast?

As a random fun side note, the fastest person I have ever seen in person at the high school level was Morgan Scalley. I competed against him in football, but where I really saw his speed was on the rugby pitch. His speed was something otherworldly. His HS offensive coordinator is on record saying he timed Morgan at 4.37. I had a WR on my college intramural team who ran a 46.9 400 in college and an 11.1 100 m in high school who said he ran a 4.4. He was certainly very fast. But Morgan made me question my understanding of speed.