The 39-year-old had season-ending surgery after he tore two ligaments in his right knee Jan. 23. Late in the 2016-17 season, he tore two ligaments in his left knee, and then hobbled through a six-game loss to the Edmonton Oilers in the Western Conference First Round before offseason surgery. San Jose needs Thornton to stay healthy if it hopes to make a serious run at the Stanley Cup. He's an elite passer with 1,030 career assists, 12th in NHL history, and a huge presence in the locker room. Thornton is expected to be the center on the top line, with Kane on his left and Pavelski on his right. The Sharks sent third-line center Chris Tierney to Ottawa in the Karlsson trade, and fourth-line center Eric Fehr signed as a free agent with the Minnesota Wild. They can't afford to lose their first-line center too.