Carolina clearly violated the rule. They had an agreement with Stevens. We apparently made an offer, which turns into an agreement if accepted. Gray area.
And did we couch it speculatively? Perhaps the communication was: 'Please don't immediately sign with Carolina after the draft. We should be in a position to guarantee you twice as much money after the draft. I'll give you a call then.' Is that a violation?
Does the NFL rulebook define "agreement"? Otherwise, it's pretty ambiguous.