There is not one player that "solves the problem" for any team, the closest thing is probably a QB and even that is a stretch.
We really should try to look at this team with a more realistic POV, winning a SB is really a tough task for any organization, just look at Philly with their super team last year, and now is loosing a bunch of pieces left and right. SanFran has had some good teams since their last championship, they have been a though talented team last decade and what do they have to show for? Thats right, zip.