Matt Cassell, signed in the offseason to push incumbent Christian Ponder for the starting quarterback role, became a casualty of the Ryan Mallet trade this morning. With three quarterbacks already on the roster including Ponder and McLeod Bethel-Thompson, the Vikings decided to part ways with the former Chief and Patriot and his $3 million-plus salary. After releasing Cassell, the Vikings were left with two open roster spots. They filled those by signing fourth-year receiver Deon Butler and second-year cornerback Jonte Green. Both players are expected to provide depth while Butler could see himself in the lineup during three and four wide receiver sets over youngsters such as Jarius Wright, Joe Webb and Greg Childs.