Fowler came into the league with all the physical tools in the world, and took several years and a change of teams before he began to meet his potential. Even now, his numbers are good but not outstanding.
Littleton came into the league as an UFA. He had to work his way up from special teams. He was handed nothing, had to earn every move up every step of the way, and he has gotten better every year as a pro. While given he is not a strength against the run, look at what he brings in terms of forced fumbles, interceptions, passes defensed etc. And he is strong against the pass in a league that values LBs that can cover.
I would rather reward the spunky, determined achiever who earned every step of the journey than the gifted athlete who has, in my opinion, questionable motivation.
Just one man's thoughts. And I don't think Littleton will be easy to replace. Unless Jamie Duncan is still available.