Locally I usually catch one or two bass over 5, and a handful of bass over 4 each year.  This year I have only caught one over 4, and that was back in the spring.  I have tried mapping out where the large ones aren't, and fishing different areas, but that hasn't worked either.

Jig , worms and topwaters have always got me my biggest fish. But I've got a few big ones on rapala shad raps and floaters. I know some people swear by the spinner bait.. preference comes from personal experience. 

Jigs worms and topwaters for me though. 

I'm steal  stabbing at it. Last week went lake fork and didn't catch anything over 3lbs. This week I'm at lake Sam Rayburn. Got a fat 4'9" but still shy! My buddy tho caught a 5'5" bass! I'm in the pic with the little girls. Those are his daughters. I try and come down here once a year. Still have a great time. But want a giant bass so bad it hurts!

temps were very sporadic this year, and florida stran bass seem to be more sensitive to it. I was I lake fork ist week in march this year. used mostly bubble gum trick worms on bullet nose. fished very slow we did get mostly big ones, but not numbers  .5 to 10 fish a day. lake was down, couldn't get back in where we wanted

I read the title as a BIG  ..... fish slump.   As in no fish.   Not a BIG FISH  ..... slump.    I was going to reply to go bluegill fishing, but I see that you still aren't doing to bad for yourself, even if you are in a BIG FISH slump.