Jim Harbaugh has brought many things to the 49ers since becoming head coach before the 2011 season, including a bag full of slogans.One he likes to repeat is, "As iron sharpens iron, so does one man sharpen another," in regard to the spirit of competition on his roster.In every training camp, Harbaugh and GM Trent Baalke have brought in new or veteran talent to challenge incumbents or compete for a roster opening. This offseason, after No. 1 wide receiver Michael Crabtree went down with an Achilles' tear that likely will keep him out for the entire 2013 season, Harbaugh said he is confident an open competition among the young wideouts in camp this summer will produce something good."We'll put (A.J.) Jenkins, (Quinton) Patton, (Ricardo) Lockette at the same position and let them compete and emerge," he said. "The good news is that somebody will emerge because they have to."Now, the 49ers go into training camp (the first full practice is set for Thursday) with a similar competition now ready to begin at cornerback.The Niners' trade for Tampa Bay veteran corner Eric Wright Friday should create a true iron-sharpening scenario. Wright joins a team that brings back 2012 starters Carlos...