San Francisco 49ers linebacker NaVorro Bowman restructured his contract, converting $3.3 million of his 2014 base salary into a signing bonus, according to a league source.Bowman's base salary, which was guaranteed April 1, decreases from $4 million to $730,000. The team created $2.616 million in cap space with the move.The team is likely freeing up room for quarterback Colin Kaepernick, who is in the final year of his contract.