Delta's baggage mishandlers are the worst I have seen in the industry. They have destroyed several of my bags, and they try to avoid paying for them.
I have found that if you pull out your elite card, they will sometimes waive the rule about protruding parts. At least, that has happened to me twice.
I always try to travel light and take only carryons. When the Feds restricted carryons to one, I almost put them in the same camp as al-Queda, since it put passengers more at the tender mercies of the baggage mishandlers. Two carryons had worked quite nicely to avoid having to worry about baggage mishandlers.

Now that DL motivated me to change airlines, and I have switched to NW, I have had one bag damaged and cheerfully replaced by NW. It that case, my wife's packing had probably made the contents too heavy for the bag and contributed to the damage but they did not even quibble about that. NW is so much easier to deal with than DL.

Back when I used to fly Eastern regularly, I seemed to often have bags temporarily misplaced, but never damaged. Having flown quite a number of airlines in various countries, I have never seen one as bad about luggage damage or dealing with it than DL.