After seven years with the San Francisco 49ers, Adam Snyder signed a five-year, $17.5 million contract with the Arizona Cardinals before the 2012 season. Last season Snyder allowed four sacks, six quarterback hits and 17 hurries, and received an overall score of -20.1 (which isn’t good) according to Pro Football Focus. So the Cardinals drafted a guard (Jonathan Cooper) in the first round and released Snyder, even though they gave him a $5 million signing bonus a year ago.

Snyder started every game for San Francisco in 2011, but replacing him with Alex Boone was considered to be a large reason why the 49ers’ offensive line was among the best in the NFL last season, if not the best. As a result, many observers figured there was no way Snyder would return to San Francisco. For example:

Fast forward to a week later, when the 49ers made this announcement:

The San Francisco 49ers today announced they have signed G Adam Snyder to a two-year contract.

Snyder (6-6, 325) has played in 121 games (83 starts) during his eight-year NFL career. He returns to San Francisco after spending the 2012 NFL season with the Arizona Cardinals, where he made 14 starts.

Alrighty, then. Why would the 49ers bring back a guy they weren’t all that interested in a year ago?

1. Competition

While the starters on the offensive line were incredibly good and durable last season, the 49ers have to prepare in case of injury in 2013. That’s not easy because the 49ers didn’t make the o-line a priority in the draft, so Snyder is probably there to keep Daniel Kilgore and Joe Looney from getting complacent. Others vying for roster spots on the line include two guards (Al Netter and Wayne Tribue) and two tackles (Kenny Wiggins and Carter Bykowski, who was drafted in the seventh round out of Iowa State). The 49ers also added two offensive linemen as undrafted free agents: tackle Luke Marquardt and guard Patrick Omameh. As Eric Branch pointed out, none of those other linemen have ever made an NFL start.

2. The 49ers know well enough to ignore recency bias

We pretty much have to go off PFF’s stats because nobody else does a comprehensive job of judging offensive linemen play in and play out. Snyder probably wishes we didn’t, since he scored just as poorly in 2011 (-21.2) as he did in 2012. But Snyder earned a respectable score of 3.0 in 2010, when he didn’t allow a sack in 271 snaps.

3. The Cardinals vastly overpaid

It probably wasn’t that the 49ers were keen on letting Snyder go, but they generally stay pretty rigid with their salary slotting. If another team comes along and goes way over what the 49ers feel a player is worth, they never stand in the way. That’s why Ricky Jean-Francois, Isaac Sopoaga and Dashon Goldson are now members of the Colts, Eagles and Buccanneers, respectively. A $5M signing bonus is one thing, but a two-year deal at the minimum (that might have nothing in the way of guarantees, by the way) is another story.

4. Familiarity/Personality

Snyder has worked alongside both Jonathan Goodwin and Anthony Davis in the past, and he has experience working under Greg Roman and Jim Harbaugh — who’ve created one of the most complex set of formations and plays for offensive linemen to learn and implement. He’s also by all accounts a good guy (I think we can trust Matt Barrows on that one), and after his release Snyder had this to say: