He's supposed to be near-enough comparable to Anakin(perhaps even greater), he's capable of manipulating ships a good deal pre-AotC, he can deflect a rain of debris from a destroyed ship on a DS nexus, he can pull a ship up by the nose while piloting it(it's not exactly AotC, but not too far after it), and a bunch of other sh!t on that general calibre.
Where is Anakin stated to be superior in AotC? I keep hearing about it (including a claim from Gillard) but I've yet to see it myself. Gillard implies that Anakin surpasses Obi-Wan after AotC (he mentions it in RotS as if it were a new thing, suggesting that it hadn't happened by AotC). And I've posted the quote from the TCW junior novel where Ventress reckons that Obi-Wan is more powerful than Anakin.
Its based on the statement that while aotc kenobi was no match for dooku, anakin was a challenge for him. Though given gillard's statements, ventress's, their early tcw performances vs ventress, and kenobi's ability to stalemate post tcw anakin in obsession telkentically, I think that's been beyond retconned at this point