In the spring bass are feeding up for the spawn and when the water warms enough their metabolism is increasing causing them to want to feed more often. Also the warmer infux of water in the spring will cause the crawdads to start moving about - which is why the red colored baits work so well. Then you combine the shad kills which "sparse" out the food source and you have the predatory responses to dying fish making for easy prey - thus "slow rolling" (so to speak) your rattle trap type baits (like KVD and others were doing) it imitates the dying shad so well they scarf it up.

In the fall, it is all about putting on weight and schools of shad are the most abundant forage to do that, most lakes primary food source is the shad.