It seems then a bit of an issue from both the seller and Pitney bowes. The seller really should have put your MIB doll in a box for protection. Even though they may have put layers of wrapping around her, that wouldn't save her box from being squished by something heavy in transit
..however, the damage to the box does not appear to be due to damage in transit. It definitely looks to me like Pitney Bowes just sliced it all open with a knife to check the contents (damaging your box in the process) and then taped it up again leaving it in the sellers original wrapping as it couldn't possibly be packed much lighter
I would complain to ebay. Its not completely your sellers fault... they have part blame but they didn't cause the damage, nor was it damaged in transit from those pics and your sellers description IMO.
I would phone ebay rather than email them and let them know the situation then ask for advice. You usually get better response from them with a phone call rather than emailing them and I don't think I'd just go ahead and open a case yet - I'd call for advice first . Please let us know how it goes