Im not denying that skill is a great part of it (depending on the situation, enginekill in a cap can mean death for a bomber if you fly right, and the bomber is slow to realize what yourdoing) and that weps loadout is part of it (make great use of propper weps groups) but the fact is that its EASY for a bomber to hit a cruiser or up, while its VERY hard for a cap to hit a well flown bomber (falcattastrafes amazingly, for example, and when used in a intelligent way, caps die like flies)
However, whats the point of caps in the first place if all you need a pair or 3 of bombers for each cap. Just spam bombers and dont bother with caps at all. Caps should have defence against fighters/bombers at closer ranges, forcing them to stay farther out.