This paragraph really tells the story:

Some personnel people are convinced the market for Cobb will be between $9 million and $10 million, but they're often conservative this time of year. It wouldn't be shocking, given the number of clubs flush with cap space, to see a five-year deal for Cobb averaging $12 million, perhaps even $13 million with guarantees well in excess of $30 million.
If Cobb sees only a million a year difference, I think he wants to return and might give the Packers another shot to offer before Tuesday.

But if the difference is between a 8-9 mil average and 12-13, then its a no brainer.