I try and stay out of the forums, but figured I'd throw in my point of view on the matter. Xzil is absolutely right, the fact is that the republic has a lot larger and stronger player base for both PvP and PvE. That doesn't mean that the imperials don't have any good players, because we do have our fair share, but we have a lot less of them.
When it comes to pugs and solo queuing, it is very common to find yourself in a group where everyone else has terrible gear, no expertise, or are just plain stupid. To try and alleviate this occurring, imps find themselves grouping up and queuing in strong 4-mans. In my experience, when I do this, I very rarely loose. This is because when we find ourselves in tough matches we play for objectives, not numbers.
Long story short, imperials are generally forced to group up if they want to win, while the pub's larger and more experienced player pool allows them to solo que and still do well. I think that the creation of battle groups could help fix the imbalance, but until then if you want to win on imp side grouping up is your best shot.