While I congratuate you on your number crunching, I've always wondered where the "cut line" for combine results really are for each position.
Since combine skills don't necessarily translate onto the field, what may be the general "cut line" for these tests that suggest they can't cut it on the field? Does a 7.7 in the cone drill mean they can't be a first round pick? Why? Does it really matter?
If all things are "generally" equal, instincts in sports are very critical, if not THE critical factor that separates the players.
In other words, do they "play fast" or even play stronger, tougher - jump higher on the field?
Instinctual timing, getting a jump on the play, knowing how to use your body (etc) can't be measured in combines. You can shave a second off your shuttle speed on the field because the cones are moving and you just "know" how to get around them faster than the next guy, you can out jump taller players because you "know when" to jump, you could out muscle bigger opponents because you can use your leverage.
And if you don't know where you're going on the field no amount of speed will get you there.
[My favorite example is great outfielders. They are great not because they're the fastest or have the strongest arms, but because they know where the ball will go and get a "jump" on it, shaving a great amount of time of their "40". ]
To me, as long as the times are generally the same the only way you can tell the difference between one or the other is what they did on the field and do they possess the capacity to "learn" how to be faster, stronger, quicker on the field.