Should point out here: Gold League in SC2 means that you’re an ‘average’ SC2 player. The way SC2 works is:
Bronze: Bottom 4% of players.
Silver: Next 23% of players.
Gold: Next 23% of players.
4+23+23=50.
Or to put it another way: 50% of all starcraft players are in gold or lower. The other half is in platinum or higher.
So here’s the kicker: AoE2 and 3 start you with an MMR of 1000, which goes either down or up depending on whether you lose or win matches. MMR 1000 is the middle value. In SC2 terms, that means you’re facing people in either the gold or platinum league at the start, before slowly being kicked down to your proper place in gold or silver. That’s gonna hurt when you’re still getting your footing.
That doesn’t mean you’re bad at RTS games: You’re just getting ranked in a pool of people who are currently playing AoE3 online, and there’s a lot of self-selection going on there. I don’t doubt that you’re smart, fast with your hands, and have been around the RTS block… But that goes for all your opponents too, and chances are a lot of them having been playing AoE3 a lot longer then you.
This evens out: The point of MMR is that once it’s settled, you get to fight against opponents that you have a 50% chance of winning against statistically, and obviously you accrue some experience along the way. It’s just that you’ll have to bite the bullet at the start.
And just like with SC2’s gold, just becuase you’re an “average” ranked player (or “below average” in AoE3) doesn’t mean you’re an average SC2 player. It’s a highly competetive scene. Even someone who gets to gold is going to be better at SC2 then most other RTS players, but most of them don’t play online ranked to begin with. It’s a bit like finishing 5th out of 10 at an olympic sprint. Sure, you’d rather have won, but also, you’re still a faster runner then anyone watching.
Tl;dr:
The statistics that AoE3 uses assume that any player who starts playing ranked is going to be able to beat 50% of the online ranked playerbase. This is almost never true for a new player, so the system will overestimate your skills until you’ve done a bunch of matches.