Blue Shield of California issued a counter offer to Sutter Health on Wednesday that would extend the previous contract between the two companies through 2016. Sutter proposed earlier this week that Blue Shield let patients keep their Sutter doctors until the end of this year. The two salvos in a nasty contract fight between one of the largest health systems and one of the largest health plans in the state sound good for patients but protect the special interests of the one behind the offer. Unable to reach agreement on terms for a new contract that covers thousands of members in Northern California, Sutter and Blue Shield let the old one expire on New Year's Eve.