I don’t necessarily like the depth idea, but a few of the above make sense.
Could seem worse simply because for a chunk of the spring there are fewer fish around, And the remaining browns may be coming up more covertly/after dark.
April 22, 2015, I happened upon 3-4 big browns going suicide on bwos. The one I hooked was 21” and there was definitely at least one that was quite a bit larger.