There were a bunch of quality undrafted free agent centers available (Tim Barnes, Kris O'Dowd, Jake Kirkpatrick, Zane Taylor, etc.) and the Bears seemed to have missed them all. JA and company must either have a lot of confidence in the recoveries of Kreutz or they're just blind... Now we'll have to wait and see what Alex Linnenkohl can do. Hope he's gonna stay and learn from Kreutz, then maybe he can start next year.
Don't know why you're saying that lb when only Barnes rated very far ahead of Linnenkohl in the NFP pre-draft rankings. You could toss a hula hoop around the others and not find one much different from the other as far as their rankings were concerned. I don't know what made Barnes rate higher (6.4) but apparently it wasn't enough to get him drafted. The others all rate 5.8 to 5.5 which is clearly free agent material.
All I can think of is that the Bears had the opportunity to evaluate Linnenkohl while they were looking at Paea and liked what the saw. If we sign Olin for another two years, which makes sense, either he or Brignone will have plenty of time to understudy at OC.