Running back Jamaal Charles has put up some amazing statistics since his breakout performance at the end of the 2009 season. Last year, he averaged 6.38 yards a carry, a mark of efficiency unknown since the AFL merged with the NFL in 1970. Charles was so productive that the Chiefs' offense made a first down on 30.4 percent of his carries. An elusive talent, he also has been an oddly rare sight. Last year, he shared the job with Thomas Jones, who actually finished the season with more rushing attempts. Was Chiefs head coach Todd Haley protecting his best asset or wasting it by restricting Charles to half-time duty? The season-ending knee injury that the running back suffered in the second week of the 2011 season settled the argument. Charles is immensely talented. But he needs to be handled with care.