At the start of the game, it is stated, that _all_ of the Emperor's Executors betrayed him. Also, the first of the Executors we meet doesn't really seems like a talented stateman (through, to be fair, we only see him at his lowest). This... somehow do not picture the Emperor himself in a very favorable light, which contradicts both his reputation and his successes in building his empire.
What I meant to say, this seems like a logical discrepancy which really bugs me (as all those things are important to story), and I hope it's explained somewhere later in the game.