They're a bunch of oxygen thieves who are holding you back. Either make them into useful people, get rid of them or have them guard the bees.
Same point with more nuance (arguably):
The BAs are essentially doing what would the job of the product owner and the customer should be doing. Potentially the preparation of stories is too much work for your PO to handle and they need extra help. Clearly they don't need this much help, as you have a massive amount of inventory.
I mean inventory in the lean sense. Work in progress that cost time to make, costs time to keep track of, and will probably have decayed into uselessness by the time you need it. This last one sounds particularly true, as I imagine your PO spends a lot of time reworking out-of-date specifications (or at least I hope they do). Additionally, this massive pile of over-worked specs kind of makes a joke out of the idea of being responsive to change, and erects a barrier (in the time) between the customer and the developer.
These BAs are getting in the way of communication between developers and the customer. Traditional software development has a lot of gatekeepers that separate the developers (and other "low level" minions from the customers). One of the key values of agile is a rejection of this, communication is key. I've had BAs who see themselves as owners of the communication between the customer and developers, and it just adds confusion and delays feedback. The fact that additionally your BAs won't talk to develops is just appalling.
So what can you do with these people?
Perhaps there's something your team actually needs that the BAs are capable of, like testing or directly assisting your PO?
That's easier said than done. How do we start being more effective within the current status quo now? Here are a few of my ideas. I've had a few guesses at what problems the BAs are causing, but spend some time with your team doing this, and come up with your own solutions.
The work is out of date and not valuable: There's nothing wrong with ignoring or throwing out someone's contribution if it isn't a positive one. Make your your PO + development team does rework needed in communication with the customer.
Lack of communication with the customer: Circumvent the BAs during the rework and talk straight to the customer.
Lack of "agility": Use this communication to ensure that the customer can come straight to you guys with the stuff they actually want done urgently.