1: Some titans have an easier time taking out large fleets by themselves. The TEC Loyalist titan can pretty much be left alone as long is it has it's self-repair ability available.

2: Ogrovs maybe? Ogrovs deal massive damage to starbases and pretty much kill them in seconds. They are the first targets to take out in an enemy fleet and usually reguire either large numers of strikecraft or a protective fleet. of your own. Corvette swarms do massive damage to starbases, too. They are hard to targt with regular weapons, making them hard to counter with a starbase.

Yep even a TEC loyalist titan cant take on pirate base after 3-4 hours,however give it a 3 of TEC Dunov Capital ships can wipe out any pirate base granted you gave the shield recharge ability,your titan has the AOE lightning attack thingy and recharge ability.For other factions its nearly imposible to destroy pirate bases without losses.

Unless you're playing versus a player, or a horde of Ogrovs, I'm surprised. Some advent abilities maybe? I'd be curious for some more details on the situation. Even without the defense fleet I have a few worlds away, a pair of starbases aren't something that should be brushed aside.

EDIT: A lamer, AI exclusive "tip". If the bottleneck is really a high threat area, and it has to hold... Park an Akkan behind the starbases. Not only does it usually get prioritized higher, drawing in more attention toward it and through the starbase fire, but with a couple levels of targetting uplink, the starbases can outrange an Ogrov. Ion bolt helps mitigate as well. As EXP comes quick when there is actual fighting, you should always try to leave SOME capital in the grav well if you cant. Throw in whatever other tactical slot structures you want, say twin docking bays for 100% uptime, and you have a freakishly tough nut (for the AI) to crack. A player with a brain would probably eventually wreck it without fleet support, though. Booo, brains.