Smith, the 2005 No. 1 overall draft pick out of Utah, received a $4.9 million, one-year contract as a free agent last July after the lockout - when many, including Smith himself, figured he'd be headed elsewhere following six up-and-down seasons. He has thrived under Harbaugh, a former NFL QB.
The 27-year-old Smith has thrown for 3,150 yards and 17 touchdowns with only five interceptions for the NFC West champion Niners (13-3), who earned the No. 2 playoff seed in the NFC and a first-round bye this week.