Sylvanas actually creates valid strategies and plans - the losses of the Horde come from shitty writing and "necessity" of Alliance having victories despite only doing whats "honorable". Battle for Undercity is best example - Sylvanas had everything planned, with plan B and C following it, Alliance tactics was just charging in - 3 times they fell straight into Sylvanas trap, 3 times they were saved by Deus ex Machina.
Similarly with Derek - what Sylvanas is trying to do is actually excellent plan. I half seriously expect this cuck Baine to ruin whole plan by telling his friend Anduin what Derek's true purpose is. Still, either that, or this plan will fail too with absurd coincidence and Alliance luck.