When the 49ers lost to the Carolina Panthers in early November, it was an ugly performance by San Francisco's offense.In a 10-9 loss, Niners quarterback Colin Kaepernick was sacked six times, ran for just 16 yards, completed just 11 of 22 passes for 91 yards and the Panthers defense smothered his wide receivers. Mario Manningham and Anquan Boldin combined for six catches, but their total yardage was just 53 – only 8.8 yards per catch.But when the 49ers travel to Carolina Sunday for a rematch with the Panthers in the NFC divisional round, Carolina's terrific defense will be challenged by a much more complete and dynamic offense than it saw at Candlestick Park two months ago.The return of wide receiver Michael Crabtree – as demonstrated in Sunday's 23-30 wild-card playoff victory over the Packers at Green Bay – has transformed the 49ers.In the victory over the Packers, Crabtree had eight catches for 125 yards and was targeted 13 times by Kaepernick. With temperatures barely above zero, Crabtree was catching Kaepernick's darts, even in tight coverage. On the final drive for the winning field goal, he started the march with an 11-yard grab, then gained 17 yards on a...