My question is, where are you getting these values for PBU vs Interception and TFL vs TL? Have you tested how well they would have predicted the production of previously drafted players?
Great players have come from a lot of different statistical productions and so have bad ones. Richard Seymour was great for three years at Georgia but Kris Jenkins only lived up to his potential his senior year and he turned out fine.
Kevin Williams of Minnesota wasn't all that great statistically until his senior year as well but he's turned out fine.
Al Wilson didn't put up great numbers at all at Tennesee but he's been a fine player in Denver's defensive system:
DEFENSIVE STATISTICS
STATS GP/GS TK SO AS FR FC INT TFL PBU SACK
1995 12/ 0 25 17 8 0 0 1-0 2- 4 1 1.0- 7
1996 11/11 87 61 26 0 2 0-0 8-30 3 1.0-10
1997 11/11 83 56 27 0 1 0-0 7-23 3 5.0-11
1998 9/ 9 77 54 23 2 5 0-0 6- 7 3 4.0-41
TOTAL 43/31 272 188 84 2 8 1-0 23-64 10 11.0-69
Meanwhile, Napolean Harris put up far better numbers than Wilson did but he's been a pretty good bust so far (sorry for not putting up the stats, it gets tedious).
Chris Mcalister was pretty consistent with interceptions for three years, getting 6/4/5 but his pbu went 5/5/15.
And for some reason, Wisconsin defensive players, DTs and CBs have put up great numbers but have done little in the NFL.
I think stats are great when there are also good scouting reports attached. If for linebackers/DEs they say they have good instincts, hand usage, shedding ability, change of direction or for DBs they say they have good footwork (do not take false steps in transition) and instincts in the zone and etc. But they shouldn't be used, I don't think, by themselves to rank players.