3 players should never be more than a speed bump to 15 players, if they even notice you at all. Including mechanics that let 3 people hold up 15 is why the game has such a problem it does now.

If you cannot defend it you shouldn't have an artificial crutch or bullshit game mechanics to help you hold it.

Dread, if 3 people are only supposed to be a momentary speed bump to an attacking force of 15 or so, how do you propose that any guild actually hold onto a keep? If the only way to hold onto a keep is for your guild to have no fewer than half a warband of people at all times just standing around inside the keep doing nothing, then nobody will ever defend a keep. And you know what an undefended keep is? PvE. Extraordinarily boring PvE, at that.

I wonder if you've actually played WAR? Because if you had, you'd probably know that one of the longest-running complaints about the game is that since keep defenders never get loot, people already don't do enough keep defense. Instead, roving warbands abandon their keeps as soon as they capture them and set out in hopes of finding another undefended keep to siege for its loot. Sure, playing it that way is loot-efficient, but it's not terribly XP-efficient, and worse than that, it's *boring.*

The 3 versus 15 example I picked wasn't random, it was one of the most-fun fights I was ever in. I was the only one near a friendly keep in Ostland when a smallish warband, probably about 8 or 10 people, decided to PvE it. I yelled for help, and got 2 more people very quickly. From the relative safety of the keep walls, we managed to hold them at bay for a while, and that initial engagement ended with a team wipe on their part, and all but one of us down. By the time the other 2 of us got back, we'd recruited another 2, and I think so had they. They got through the door this time, and the 5 of us *just barely* held them off at the ramp to the Keep Lord's room -- we held them off until the door respawned, and that gave us a chance to return from the respawn points.

The whole time, we were recruiting like mad. The final fight ended up being a very nearly full warband on their part, at least 20 people, probably more, versus something like 17 or 18 of us. The defenders had held out long enough that our friends had had time to log in their tier 2 alts, fly them all the way to Ostland from wherever, and make it into the keep. With closer to matching numbers, the attackers had no chance at all.

But here's the thing: those first two assault waves were won by whisker-thin margins. We could have easily lost either one of those fights, and if we had, that would have been the end of it, period. 3 people held off 15 long enough for reinforcements to arrive thanks to the innate defensive features of the keep, but it also took serious determination, effort, and skill; if that group of 15 attackers hadn't been a poorly coordinated pick-up group, that would have gone quite differently. And I'm absolutely sure that everybody involved had fun.

Was it XP-efficient? Not terribly. It was paying good amounts of renown (PvP XP), way better than swarming undefended keeps, but at the time of that fight, not great leveling XP (I gather they've since increased leveling XP for participating in keep sieges.) Was it loot-efficient? Heck no. But it was the most fun I ever had in an MMO. And it wasn't the only time something like that happened.

I think the existing design for keep sieges (not fortresses, just tier 2, 3, and 4 keeps) is as very nearly perfect as any MMO's PvP system has ever been. I didn't quit because I hated keep sieges; I quit because there were 3 or 4 really huge exploits that people found that ruined keep sieges, and EA laid off all of the GMs who had been in charge of policing for exploits, and it was taking Mythic way, way too long to fix them. If they make it even easier to zerg a lightly-defended keep, that would make me even less likely to come back. What would make me come back would be if instead of adding an extra ramp into the keep lord's room, they made it so that Magus and Engineer turrets can't shoot through floors and ceilings, and if they made it so that the Keep Lord just plain absolutely can NOT leave the room he's in, or if they rehired the GMs and the level of policing against exploits was draconian enough that people were afraid to exploit.

This looks to me like Land of the Dead: another "fix" that's actually making things worse instead of better.