These crazy 3000-7500 numbers are always thrown around but the "real" competition is probably a lot less. How many of that X000 complete the application, put some time into answering the questions and meet the basic academic criteria? How many are just applying because they saw an ad on Facebook (other social media is available) and thought the job sounds cool?
And with BA FPP specifically, it's been proven time and again that you're competing against a standard, not other people. Except for perhaps the first stage, if you meet the (undefined) criteria, then you will be put through.