I think most people make the mistake of using too narrow of a grip on close grip benches. You only have to position your hands about 10-12" apart. Anything less is going to put extra stress on the wrists. The key to getting anything out of the close grip bench is not so much the hand position but the elbow position when bringing the bar down. The elbows should be tucked very close to your body with elbows pointing towards your feet. If your grip was any closer than 10-12" apart, you would have a hard time coming all the way down with your elbows by your side, then you would be taking away from the triceps. Most people do not keep their elbows tucked by their side and thus do not ever get anything out of close grips. Proper form is everything on this excercise.
I went from doing 155lbs for 12 reps last year to 265lbs for 10 reps this year on this excercise. I made the same mistake as everyone else in the beginning, I did not keep my elbows close enough and my grip was too narrow causing pain in my wrists with my work sets. Form was the culprit, now that it has been corrected I am close gripping like a madman.