Federer believes in percentage tennis. Therefore on Deuce side, if he goes out wide, it often will be sliced. Not very surprised. EDIT: Same with both Berdych and Monfils: http://www.rolandgarros.com/en_FR/sc...y7/1133ms.html
Seems hitting out wide on deuce court when you're righty is so efficient that you don't need to crush the ball on that side. This is also the direction, along with on body deuce side serve, that gave Monfils the most aces with 6 out of 26. It is also the direction that allowed him to win the most service points on his first serve with 24 points won on that side. Although on second serves he was more lucky to go "down the T" on deuce side: 12 points won there.
Looking at some other match stats, the out-wide deuce serve isn't always the slowest, but it doesn't shine by its speed either. Common threads?