Smallmouth in the PI Bay, have patterns changed in the past couple years?

I'm kinda scratching my head on this one and I need some friendly advice from some other smallmouth folks.
 
I've been fishing Presque Isle Bay for about 6-7 years, mainly the last 2 weeks of April to Mid May.  For about 4 years the bay was HOT for us, we couldn't do wrong.  We had days where we would fish the bay and catch 60+ smallmouth in one day between 2 people.  Late April was always best and in towards May the fish seemed less congregated in groups and numbers caught went down.
 
The last 2 years have been a bit more tough in the bay.  Our numbers are way down, we may only catch a few to maybe 20 smallmouth in one day in the bay.  I was just there Friday - Sunday and while we did catch more fish than the previous Sunday it was another less than banner weekend according to previous years benchmarks.
 
The weather temps, water temps and patterns from what I can recall haven't changed much at the times we've went in the past 6-7 years.  Our fishing methods haven't changed much, still using tubes and a few other baits for the most part.
 
Has anyone else noticed this?   Is it just me?  Just looking either for a nod that "yes" things have changed or "No, you need to change your fishing tactics!"
 
I'm hoping we can keep this educational and am looking to get a good discussion going.

according to research, (not in lake erie) smallmouth populations are VERY cyclic, more so than other fishes.  Conclusions drawn in these studies relate this to preferred food bases in that smallmouth are somewhat more particular than other species.  I haven't fished the bay for smallies much but if I did I would use my fishing mantra "find the food".  I am sure that I will be bashed for this, but on species that I fish for a lot, other than muskies my log book includes stomach contents of one keeper.