By the way, ILBs in a 3-4 are looked upon to shore up the run defense first, cover second, make plays third. Athletic/fast LBs succeed in the 3-4 D, so maybe the Texans brass wanted a LB that fits their system, not one that has looked good on paper.....besides, those Pro-Bowl players you mention:
Spikes, Suggs, Porter, and Brooking...they all play OLB! Porter & Suggs play OLB in a 3-4!
As for the ILBs from the Pro-Bowl:
Lewis - 147 tkls, 1 sack, 1 FF, 0 INT
Farrior - 95 tkls, 3 sacks, 3 FF, 4 INTs
Bruschi - 120 tkls, 4 sacks, 2 FF, 3 INTs
Dan Morgan - 102 tkls, 2 sacks, 1 FF, 2 INTs
Trotter - 61 tkls, 1 sack, 0 FF, 0 Int
So then Farrior is the stud in the bunch: Greenwood would be between Lewis and Trotter! According to numbers.
If the only tool you have is a hammer, every problem looks like a nail.