Well, obviously all of us are homers for our guys. And please don't take anything I'm saying as trash talking. I'm just stating the way I see things. And tackles isn't a good way to measure things because we all know Thoams is the kick of diving on the pile and getting tackles.
Seriously, the best way to measue a LB's worth is big plays they make - tackles for lost, forced fumbles and fumble recoveries, sacks, and ints.
First things first, please don't even say Spikes and Spragan name in the same sentence again. In 2004, Spikes was the best OLB in football, and IMO, the best LB in football. Spikes forced 3 fumbles, had 5 picks, 3 sacks, and 2 tds while playing on the number #2 defense in the NFL.
http://www.nfl.com/players/playerpage/12722 Those are amazing numbers for a LB.
The rest I pretty much agree on. I definitely think Fletcher in underrated and Thomas is a little overrated. Still, I give the edge to Thomas. As for Crowell and Crowder, it's pretty much a toss up. They are both young players, though Crowell has made more big plays. Spragan is a career backup who is without a doubt the weak point of your core and doesn't really belong in this discussion.