It could be that bombers are better or more organized. Though I don't have proof, I'd also bet it's related to the toughened Panzers with new spawn points. I've personally noticed three things. First, more folks are rumbling around in Panzers than before, probably because the survivability has gone way up. Second, Panzer travel time to bases has been greatly reduced with the advent of new spawn points -- another incentive for more folks to hop into 'em. And third, Panzers seem to make it a lot closer to fields than before due to the above-stated reasons, possibly close enough to do some real damage.
Think that might be the cause?
-- Todd/DMF