For the upgrade I believe it is 9 sim sessions compared to the 5 that the DEC's with Airbus experience get. Thus the beancounters figured it would be cost effective to hire DEC's. As the package did not attract the required candidates, the criteria changed and experienced non Airbus Capts were hired which invalidated all the cost savings as they were put on the long course anyway...and as rtp notes the FO's with the route/type/SOP experience were knocked back...