Really like the 917 head covers and have had no issues in my mid size Titleist cart bag. Have other Titleist head covers (Open Championships Limited Edition) with no "sock" on the bottom and have no issues with them either.

I actually had the same issue. It happened on my 816H, which is the only graphite shafted club in my bag that doesn't have a long sock cover protecting it. My 915 D and FW head covers have the sock so those were not affected. The top cuff side handles on my Titleist 14-way cart bag have a somewhat textured surface finish. As a result, the 816H shaft started to wear. Eventually it wore through the cosmetic layer, into the outer core. I brought this to the attention of Titleist and they requested I send in the shaft for review. A couple weeks later I received a new replacement shaft from them. They are the best golf company out there. Hands down. I would call them.

We can't be the only people who have experienced this issue. I would bet their new cart bags will be designed in a way that protects against this problem. But, I already have my eyes on a new 2017 Mid Staff Bag, which as Chuck mentioned above about his 2016 version, there does not seem to be an issue with the Mid Staff Bag design relative to the newly-styled, shorter head covers.

BTW, in order to continue using my cart bag without it doing damage to the shafts in the meantime, I put some stick-on protection/felt-like material on the inside of the side grab handle (where the chafing was occurring) and have not had any problem since.