Miller, 31, injured all three ligaments in his right knee in the Steelers' 15th game of 2012, and had surgery on two of them, allowing the posterior cruciate ligament to heal naturally, the Pittsburgh Post-Gazette reported Thursday.
"It's too far away to speculate," Miller said in Wednesday, standing in street clothes at the Steelers' practice facility. It's still going to be a long process. You don't know how your body reacts. It's too early to tell."
Miller missed only four games in his eight-year career before the injury. He became a starter as a rookie in 2005, and led the Steelers in receptions last year with 71, the newspaper said.