According to Business Insider's Mark Wilson, Kinect is unable to pick up some of the more subtle movements of the human body, such as wrist movement. He noticed this when playing the bowling game featured in Kinect Sports. He was told by the developers that "the game can't track spin based upon a twist of [the] wrist"--an unfortunate quirk considering its importance in the sport of bowling.

Although Kinect can do a lot of things, finer wrist movement isn't one of them--an area that both PlayStation Move and Wii MotionPlus have a leg-up on it, allowing for full bowling ball control. Of course, to be fair to Kinect, it's also the only bowling game I've seen where you can literally shot put the bowling ball down the lane, which looks hilarious, even if completely unrealistic.

http://www.gamexplain.com/article-179-1277081359-kinect-cant-detect-wrist-movement.html

Might just be the game and not Kinect.

Screw moving your wrists... I'm just going to throw the ball :D:D:D:D

Also this....

I wonder what other fine motor movements are being missed.

Also, I wonder if this means  you have to make very broad movements, meaning that some games could become very tiring.

Mike from Morgantown

in games like bowling wrist movements and football the ankle movements matter alot if you want to add the spin to the ball

I didn't see any part of the story where the developer said that Kinect can't track wrist movements

It's an interesting problem. As most games depend on slighter movements, could the Kinect end up being what everyone parodied the wii as? A system that requires you to flail your body around? Otherwise, I'm not sure how well it will detect motions.

subtle movements are those movements

Quote the part where the developer said that

According to Business Insider's Mark Wilson, Kinect is unable to pick up some of the more subtle movements of the human body, such as wrist movement. He noticed this when playing the bowling game featured in Kinect Sports. He was told by the developers that "the game can't track spin based upon a twist of [the] wrist"

Seems to me like the developer pretty clearly stated that Kinect cannot track the finer movements of the wrist..such as twisting of the wrist.  If it could,  they would be able to track the spin based on the twist of the wrist and add that into the game.