I get the exact same thing from UPS. Dented up packages just left in the general vicinity of my door. No knock or ring of the doorbell. It kind of pisses me off, except for the fact that I live in a gated community so I'm not overly worried about thieves. That said, I REALLY didn't appreciate it when I ordered a new Lib Tech board and the UPS guy just leaned it against my door. For a $500 item, ring the goddamned doorbell!!!!
Pretty simple fix if your that worried about it, just request a signature required for drop off when you order things.