There were significant AI improvements, and if your playing with pirates on, the pirates are much harder... but the resource multipliers for the AI have not changed.

you could also just be rusty.

What version are you playing?

hmm... your playing vanilla.  intresting.  Alot of the AI updates and certainly the pirate difficulity was upped in the expansion packs only.

Just... make sure you know your counters, build lots of repair bays, expand FASTER, stop building hangers and turrets, stop researching useless tech... build an akkan, sova, or marza instead of a kol... standard stuff, you really should be able get your skill back up to beat hard AI no problems.

 Or, just watch a multiplayer replay.  you'll get that "Actually I CAN do that, hal" achievment in no time.

Its pretty much accepted that the AI is more aggressive (or rather expands quicker, which makes it a much better opponent) in Diplomacy, I don't think anyone bothered to check in Vanilla. Either way, you probably just aren't expanding fast enough if easy is giving you a problem. You could get away with turtling before because the AI sucked, but its really a suicidal strategy in Sins without at least half the map, and even worse with Vanilla because you don't get Starbases.

So fight fire and fire and be more aggressive yourself.