I noticed Murray sliced quite a few from his forehand side, even when he wasn't running to the ball. It's as if the slice was used as a "rest" shot, where less effort is expended, and the change of pace, spin, and bounce would possibly tire DJ into a net miss.
This worked both ways, as DJ would slice a few sometimes, and Murray missed low into the net.
Was really noticeable on a 5 year old Isner/Querry match, as a slice would affect the taller players much more than the shorties like Ferrer. Ferrer did make some unforced errors into the net when facing a heavy slice.