Gloating over a lopsided deal makes zero sense either. The terms you described are exactly the terms that could leave Polanco very very frustrated. Think Berrios and Buxton, for instance, notice? My only point is that taking your best players isn't likely to help you much.
What do you do if you're Polanco or his agent?
Polanco was not forced to sign that offer. He decided to take the stability of the contract rather than try to cash in down the road. For a guy coming off an 80 PED suspension last year along with questions regarding how likely he will remain at SS, Polanco did pretty well for himself. If he massively outperforms his contract, then both sides benefit.
If I am Polanco and his agent, I am happy every single payday to see that check hit the account.
As for Buxton and Berrios, everything depends on when they sign. They both will likely cost more than what it took to extend Polanco and Kepler.