AA did hit the ball more cleanly but that doesn't mean he was a better ballstriker.
He just used a quite moderate swing while federer swings really wristy and spinny. that means he has much less margin for error. the more spin and wrist action you have the less margin for error you have because your swing plane doesn't match the ball plane but intersects it steeply meaning you have a short time window to hit the ball.
Extreme spin always means some framing and shanking it's much easier to strike the ball cleanly flat. no coincidence that all the flat hitters look like they hit it always cleanly (davydenko, agassi, Delpo).