From IOM website it is possible to work out that they are 13% down in February on IOM routes,versus the combined FlyBe and Euromanx numbers for 2008 (after allowing for the EMX routes which FlyBe didn't take up). Included is a 24% increase on IOM-BHX.
That said, they cut capacity quite savagely on LPL, MAN and LGW during January and early Feb so their load factors and yields will surely look much better than a headline decline of 13% suggests.
They do appear quite slick at cutting capacity, even if it's just a few flights here and there on the slacker days of the week.
I'm sure you're really looking for numbers across the network, and IOM may not be typical, because of the one-off impact of Euromanx but I hope this is of interest.