I would guess rub on too long. I have cooked Smithfield often and they come out fine, unless I mess up.
For the record, I used to go to a place out here that did cure his ribs a bit, they were hammy and delicious.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"I'm Armenian...perhaps...but then again...maybe not..."