You might want to try something completely new that the fish haven't seen before like using creature baits, swimbaits, or large 10in + worms. It might be that the fish are used to seeing the same types and sizes of soft plastics, or they might have been caught so many times that they won't hit those 4in worms anymore. This could result in a bunch of lunker bass swimming around that seem to be "uncatchable." I have fished small ponds before and most of them are overfished with the same lures which are plastic worms. As a result, I have seen tons of 10lb plus bass swimming around but I couldn't catch them, so I put on a big 12in worm and caught one of the big ones. You should try it.