Staff didn't strike. ACAS got involved and a deal was reached to bring the staff in line with rest of HIAL over a period of about 4 years. A basic Google search will give you the details.
The drop in passenger numbers is obviously due to Loganair pulling out. What this masks is that all routes were doing ok before losing BHX and BHD. Pax numbers were up at the end of last year and movement numbers were up almost 40%! There is a market there somewhere but personally I don't know what it is exactly, be it business, oil, schedule or renewable oriented. In the meantime, it is bound to be a struggle to make the place work.