He was 26 his first year in San Francisco, but it was also just his 3rd year in the NFL(after 2 miserable ones with the Bucs). He'd played in just 19 games, so he wasn't really experienced enough to be ready to contribute. He didn't take over the starting job until 4 years later, and in this era of free agency, I doubt he would have lasted that long. Someone would have seen him backing up Montana, and would have took a chance on him. Just look at Rob Johnson.
