I flew out on the following Flybe departure to AGP last year when I couldn't get flights from MAN, LPL, LBA or EMA due to all being either fully booked or mega high prices. The surprise was, not only was it very cheap but it was only about one third full. It seems that demand is not that high.
Mon 17 Jul 2017 BE4427Doncaster Sheffield to Malaga15:3019:30