DJ won the US Open a couple of years back and has finished second in the last four majors. Brooks Koepka won two of the last four majors. Both of these guys are very long off the tee and have a “closed” club face. I believe they are the #1 and #2 players in the world so they must be doing something correct.
So is having the club face closed a bad thing. The other thing you will notice with both these players is an extremely bowed left wrist. Putting the left wrist in flexion make the club appear closed but is also a great wrist position for impact. While these great player are sometimes criticized for a closed clubface, millions of golfers play with an open clubface, extended left wrist hitting slice after slice. This open face also is a major power loss and very common in player who hit the ball a short distance.
I am not saying a closed face is best for all golfers. But if you slice the ball maybe you should try to get a bowed wrist. The only typical problem when a player gets the club face more neutral or closed is short term left shots. You will have to learn to rotate your body more open at impact. A simple way to think about it is the more closed the clubface at the top the more open your hips must be
Next time you go to the range try getting your left wrist flat or bowed at the top and see what happens. For most of us including me when I try to get the left wrist bowed, and it feels really bowed it is basically flat. So make sure you take a video of your swing when trying this because the feel is typically way different than the what is really happening.
Jim Hartnett, PGA