49ers Free Agency 2012: Dissecting San Francisco's Top Signings This Offseason

Following their loss to the Giants in last season's NFC Championship, the 49ers have been eager to rebuild the pieces they were missing in their quest for the Super Bowl.

Though they lost out on the Peyton Manning sweepstakes, San Francisco has still been active, picking up some of the best free agents on the market this spring—including a couple they stole from the team that ended their season.

The 49ers took a big leap forward in 2011, finishing first in the NFC West at 13-3. Quarterback Alex Smith finally seemed to fulfill the expectations many had of him as he entered the league in 2005, posting a career-best 61.3 completion percentage and throwing for 3,144 yards and 17 touchdowns.

Still, San Francisco has managed to add some serious manpower to its offense in preparation for 2012. Here's a look at some of the key additions.

Brandon Jacobs

The Giants veteran reportedly signed a one-year deal with San Francisco on Wednesday, ending a seven-year stint in New York. During that time, the running back had two 1,000-plus-yard seasons. His best year was in 2008, when he rushed for 1,089 yards and 15 touchdowns.

Over the last couple of years, Jacobs saw a big cut in his playing time as Ahmad Bradshaw emerged as the No. 1 running back. After the Giants couldn't come to terms with him on a new deal, he was released.

Though Jacobs rushed for only 571 yards in 2011, he will provide the 49ers with a veteran presence to back up Frank Gore. One concern with him, however, is his attitude: He was often vocal about his dissatisfaction with his diminished role as Bradshaw emerged, and he's going to be playing behind Gore in San Francisco, who has rushed for over 1,000 yards in five of the last six seasons.

Mario Manningham

The hero of Super Bowl XLVI is moving on after four years with the Giants. Manningham, much like David Tyree in 2008, made the biggest play of the biggest game of the year, hauling in a 38-yard, over-the-shoulder pass down the left sideline with less than four minutes remaining and the Giants down 17-15. He was forced out of bounds as he came down with the ball, but still managed to make a complete catch.

Yes, as a Patriots fan, my soul just died a little writing that paragraph.

Though Manningham has never started more than 10 games in his career, he has clearly established himself as a big-play receiver, despite finishing fourth on the Giants with 39 receptions for 523 yards.

Manningham signed a two-year, $7.375 million deal with the 49ers, a huge bargain for San Francisco and a good prospect to start with Michael Crabtree.

Unless he is unstoppable in training camp and in the preseason, though, he could lose that role to…

Randy Moss

The 49ers took the risk and became the team that bit on the former Viking, Raider, Patriot, Titan and Viking, who did not play in the 2011 season.

Obviously, having been out of the league for a year, it's impossible to know how much of an impact Moss can truly have, but at 6'4", he has always been one of the most impactful wideouts on the field throughout his 13-year career.

As part of the most prolific offense in NFL history with Tom Brady and the Patriots in 2007, he registered 1,493 yards and 23 touchdowns, and though he followed that up with three straight 1,000-plus-yard seasons, his touchdown totals have been down.

San Francisco head coach Jim Harbaugh is confident in Moss' potential, telling the Sporting News' Clifton Brown:

"

We thought he was a good move for us. Excited to have Randy on our team. Our research, we feel that the merits outweigh the risks. … Randy's got the license, and we feel like he's got the ability, to be a contributor to the National Football League and to the San Francisco 49ers. It's that simple.

"

Harbaugh, however, did not address one concern that plagued CBSSports.com columnist Mike Freeman: