I always use the better of the time from either the combine or Pro Day because not all players go to the combine. Despite claims otherwise, some players do run slower at their Pro Day, so it's not always a faster time.
Taco
6-6, 277
4.86
1.63
JPP
6-5, 270
4.78
1.68
Greg Hardy
6-4, 281
4.79
1.67
Terrell Suggs
6-3, 262
4.84
10 not listed
Joey Bosa
4.77 (4.86 combine)
1.65
Taco had the best 10 yard time and his 40 was not that far off considering that only Hardy weighed more.
The 270 pound players generally just don't put up forty times like the 250 pound players. DWare was 251 when drafted. That's 26 pounds less than Taco. Von Miller was 246.
Emmitt Smith ran a slow forty but his 10-yard time was as good or better than most players that ran a much faster forty.
Cole Beasley can't touch Brice Butler on deep-speed, but he can cut 1 yard in, 1 yard out and 1 yard back in before Butler can go 3 yards in a straight line.
Travis Frederick ran a terrible forty time but he's the best Center in Football and he plays in a Zone scheme that was thought to require smaller-quicker players.
The best indicator is the player's game footage (Game Tape for Scouts). Taco in not slow in game footage.
Players like Taco, Greg Hardy, Bosa, etc.. don't play the same style as Von Miller. The bigger players with more length rush in more of a straight line to the QB as opposed to looping around the OT like Von Miller. Bosa would be terrible if he tried to play like Von Miller. Marinelli does not like for his DEs to loop wide and deep because it takes them out of position to play run defense. Instead of having them read-and-react like Rob Ryan did with DWare, Marinelli has them rush as if it's a pass and then defend the run on the way. It's a style I prefer. I hated seeing DWare in a read-and-react defense with RR.