There is a good chance that your large bluegills have gotten smarter and tougher to catch. I had a small pond that I stocked and then didn't mess with for years. One day, I went by it and had an ultralight spinning rig with me. I caught whoppers; caught them for the next couple of times I went there. Then it all stopped. When the pond was drying up, I seined it and got some big mothers out. However, I couldn't catch them on lures or night crawlers. Bass and catfish do the same thing. They start out stupid and then smarten up quickly.
