Do you have any pictures to post? It sounded to me like they are having some transplant shock. It'll take them a while to be established and grow new leaves. If you aren't sure if you have overwatered them, try to feel the dirt around it with your fingers. If the dirt is moist, withhold water until the moisture dries up. This time of the year, the growth rate for bananas will also start to slow down, but I don't know about AZ's weather and growing condition. I think bananas start slowing down when the weather falls down to 60's-70's. If you're expecting colder weather to come, you can alays plant them in a pot first and when the weather cools down, you can bring them in. I don't think bananas die very easily unless they're diseased, or they dry up with no watering, or their root system rots with too much watering.

Thanks for the advice! I can't post any pictures, unfortunately, because there's a problem with my camera. I do think I might be overwatering, though. It's still warm here, 100 degrees today. It doesn't get too cold in the winter, it usually freezes a few times, but I can cover them for that. I think I'm going to cut the old leaves off and water a little less. Thanks again!