Earlier Thursday on "SportsCenter," ESPN Insider Adam Caplan identified an explosive receiver as the San Francisco 49ers' top need this offseason.Caplan suggested the 49ers should pursue Pittsburgh receiver Emmanuel Sanders in free agency. Caplan reasoned that Sanders will be attainable for the 49ers because the Steelers likely won't try to re-sign him.Sanders has speed and he has made big plays. He had 67 catches for 740 yards and six touchdowns last season.