49ers' defensive overhaul unexpected

Panic would have set in last season if the San Francisco 49ers had gone into a game without five defensive starters and a promising young backup safety.

Aubrayo Franklin, Takeo Spikes, Nate Clements and Dashon Goldson each started 16 games for the 49ers in 2010. Taylor Mays was a player the team hoped to develop. He made six starts.

Only Mays remained with the team by Thursday, and his future became murky following reports the 49ers had informed all NFL teams Mays was on the trading block.

Goldson, though still a free agent, knows he will not be back after the team signed safeties Donte Whitner and Madieu Williams.

What is going on here? The 49ers are going backward on defense in the short term, by all appearances. But they are moving forward with a new coaching staff looking for its own players. Sometimes teams know what they do not want before they have what they need. That could be the case for the 49ers. Only the coaching staff knows whether newly signed players on defense fit better than the ones they're replacing.

The market has justified the 49ers' reluctance to secure Franklin and Goldson with lucrative long-term agreements. Both players languished on the market. Franklin took a one-year deal from New Orleans. It's looking like Goldson will settle for an underwhelming deal as well.

The 49ers arguably would have been better with both players on their roster, at the right price. But for first-year coach Jim Harbaugh, throwing piles of cash at players unfamiliar to him would have anointed those players as pillars of his new program. He wasn't going to do that, and I understand why.

Age was an obvious issue with Spikes, who might have departed anyway. Clements' salary-cap figure made it impractical for the 49ers to keep him around. Once players get cut, they often look for work elsewhere. Clements did just that, agreeing to terms with Cincinnati.

The 49ers obviously do not think Mays fits their new defensive system. That is unfortunate for Mays and for the team, but also the price of turning over a coaching staff. New coaches tend to want new players.

Before January, there was some thought Harbaugh was coming in merely to fix the offense. The 49ers already had the makings of a strong defense. They needed help in the secondary, but an overhaul appeared unlikely. Harbaugh would attempt to figure out the quarterback situation, coach up the offense and push the 49ers over the top in the NFC West.

Those things still might happen, but it's tough to see coming. The heavy turnover on defense adds new variables to the equation.