Eastern were only ever going to be a bit player in IOM market. Their business model, pricing and available capacity ensured that. But it's not just FlyBe that have caused them problems. Manx2's GLO service killed off their BRS route in just a week or two.
Even with a totally clear run at NCL (no alternative for many miles, in any direction) their pax numbers have been pitiful. I know several people with kids at Uni. in Newcastle or Durham, but no-one would contemplate using Eastern as they are simply far too expensive.
At the end of the day, I doubt they knew the IOM market anything like as well as FlyBe or Manx2, stuck to their model, and it's not worked out.
FS01 is spot on. Their business focused operators are struggling to make it work right now - will it work again in the future - who can tell.
On the two occasions I used them, their services was great, but not worth half what what my employer paid.