Jason Hammel will be sidelined 3-4 weeks following arthroscopic surgery on his right knee. Hammel has dealt with a piece of loose cartilage in the knee for a while now. He was planning to delay surgery until the offseason, but the pain forced him from Saturday's start, and he's decided to go ahead and have the operation now. The Orioles are likely to bring back Brian Matusz to replace him in the rotation, but they're even more likely to trade for a starter now.