Bananas are heavy feeders & like a lot of moisture. Maybe you need to give them more food & water...?

I agree, I think not enough food and water maybe the problem. They like a lot of both. You could check the banana forum too, to see what they say. :o)

If you are in a warmer zone than me I would go ahead and put a bag of black cow (found at Lowes, H Depo, walmart etc) around the base and water it in good. There are specific banana fertilizers with higher potassium ratios etc. but I usually just feed mine whatever the other plants are all getting. I vary MG, fish fertilizer, plus I have chicken and rabbit compost, yard waste, coffee grounds etc.

I get bananas on my plants here in zn 9a so the fertilizer must be good enough. When the bananas aren't actively growing in the winter here I just barely water and don't feed much at all and they do look ratty. In March when they start pushing new growth, I give a bag of black cow to each stand of bananas and then start fertilizing and watering after that.