The 49ers had used three-receiver formations roughly 20 percent of the time since coach Jim Harbaugh arrived in 2011, and those came primarily on third-and-long situations. Against the Cardinals, they went with five wide receivers – never used before under Harbaugh – six times on their opening drive.Read more here: http://www.sacbee.com/2014/09/23/6728180/despite-loss-harbaugh-pleased.html#storylink=cpy
I think I don't need to comment on this one