Kuechley wouldn't be a backup for very long. He would be starting over Connors in 2 years if not before. Having Connors gives us the luxury of being able to take a Kuechley and let him develop.
In a 3-4 (if we stay with it) you need depth at ILB. We have 2 starters at the position in Lee and Connors. Kuechley would add some much needed depth at the position.