Josh Johnson signs with 49ers

The 49ers have signed QB Josh Johnson to a 2-year contract.  It's an intriguing move if only because Niners HC Jim Harbaugh coached Johnson at the University of San Diego from 2004-2006.  As a starter in '05 and '06, Johnson tossed 70 TDs vs. just 13 INTs.  Of course, his playing time has been sparse at the pro level.  In 16 appearances over 3 seasons, he's completed just 54% of his passes with 5 TDs and 10 INTs.  QB Alex Smith would need to fall flat on his face for Johnson to get a crack at the starting job in 2012.