There is a fairly obvious scenario where the Sox win:
Price pitches well from here to end of Year 3, opts out, signs elsewhere for big money, then flops. We therefore get 3 good years and someone else pays the freight on the bad years.
Like I said earlier, just look at what happened on the opt-out with Sabathia. The Yanks would have been better off letting him exercise it - which he would have if they didn't bend over and give him a further 2 years.