Can you tell us about the depth of the lake and water quality (plankton bloom in summer) and do you have water plants (submerged or emergent) and if so what % of the lake has plants?

From the limited info , you have described a little bit of an unusual status.

1 Some top end predators are doing very well.
2 Few 4 - 5 lb. predators.
3 lots of small prey BG , YP , Crappie but no large ones.

Before I make a WAG my suggestion is you need more data than just catch/creel data. Seine surveys , possible elecro-shock survey and trapping data would help. An idea of how many and what type of fish are taken out is important. Your DNR may provide these services and private fisheries science (pros) provide them also.

Here is my WAG. The large/extra large pike are eating most of the 3+ lb LMB, eyes and YP. There are not enough small predators 10-12in. LMB, YP, pike and eyes to control the small BG, crappie and YP which are all known to stunt. As a result of competition for food among the prey species there is a shortage of 6-10 in BG , YP and Crappie to feed the medium sized predators so they don't appear fat and healthy.

Who's next with a guess? \:\)