49ers' weakness: Defensive backfield

Posted by Scouts Inc.'s Matt Williamson

Instead of choosing the defensive backfield, it was very tempting to pick offensive continuity as the weakest aspect of the 49ers. San Francisco has gone through an amazing seven offensive coordinators in seven seasons. Such change has been extremely difficult on a young quarterback such as Alex Smith.

Along those lines, quarterback very easily could have been the subject of this blog item as well. Also, outside of the offensive line, the 49ers have only two offensive players (Frank Gore and Vernon Davis) who should feel safe in their starting positions.

That is a difficult formula for winning in this league and also has added to making life difficult for San Francisco's secondary. The pass rush also has not been great, but the 49ers need the secondary to create more turnovers and step up its level of play on the back end.

Walt Harris was lost for the season in a recent minicamp, and that loss makes an already questionable group even more worrisome. The signing of Dre' Bly does help make up for the loss, but it also should be considered a step down.

Nate Clements is a good player, but not an elite one. He is a physical player who also contributes against the run and does a number of things well. But his coverage skills aren't at the level of Nnamdi Asomugha and Champ Bailey.

Tarell Brown has a fair amount of upside and could be a surprise player as he matures. But he doesn't match up well against the Seahawks' or Cardinals' third wide receiver option at this point.

Brown will compete with Shawntae Spencer for the third corner spot. Spencer has good size (6-foot-1), but he has been more of a liability than an asset since joining the team.

That leaves the 49ers with four corners who should see the field, but Clements is the only one who can be considered above average. Bly might be better off as a third corner and Brown and Spencer are closer to fourth corners than true No. 3s.

Safety Mark Roman was a constant target a year ago and really struggled as a deep support player. If starting again in 2009, Roman has to be viewed as the weakest link of this secondary. The unproven Dashon Goldson is working with the starters for now and must prove he can stay healthy. Regardless, free safety is quite possibly the worst of San Francisco's starting 22 position players.

Michael Lewis still mans the strong safety spot. He is a heavier guy (222 pounds) who is at his best in run support near the line of scrimmage. He is also very tough on opposing tight ends and overall, is a very solid all-around player.

Over the past several years, finding weak units for San Francisco was a very easy assignment. That has changed, and this looks to be a team on the rise under Mike Singletary, who may change the losing culture if ownership is patient with him.

Scouts Inc. watches games, breaks down film and studies football from all angles for ESPN.com.