A 3-4 defense?
It made sense to me, given the depth at DE and LB. The Lions needed to drop at least one of Stafford, Johnson or Suh from a long term deal.
Ngata leaves about 9 million to offset the loss of Suh.
IMO, 2015 is a damage control season with 2016 being more promising due to the 9 million and 5 million in dead money being paid for Suh and Houston no longer being an issue.
Now, if only they can draft well for the trenches with the first three picks.