Same as football. I played in the late 70-early 80's and if you ran a true 4.50 or better 40, you were FAST. BIG lineman were 250# and ran over 5.2 40 yd times. Now these guys that play linebacker are 235-250 and run sub 4.5. Lineman are 300+ and run 4.7-4.8, crazy. The new generation are so much more physically trained to the task. I don't care how good guys were back in the 70-80's, these current players would eat their lunch.