GREEN BAY, Wis. -- A breakdown of the first week of free agency for the Green Bay Packers:

The Packers' signing of tight end Martellus Bennett was made necessary as contract talks with Jared Cook broke down. Maddie Meyer/Getty Images

Most significant signing: For the first time since 2012, Packers general manager Ted Thompson signed an actual unrestricted free agent. Not a player who had been cut by another team, but a bona fide free agent in Martellus Bennett. Here’s the rub, though: He basically just replaced Jared Cook, whom they decided to let walk after a difficult negotiation that broke down at the eleventh hour. Bennett might be a slight upgrade over Cook, but it’s essentially a wash. The addition of another tight end, Lance Kendricks, who was released by the Rams last week, fortified the position, giving coach Mike McCarthy the option to use more double-tight end sets this season. Last year, the Packers ranked second to last in the NFL in snaps with multiple tight ends on the field, according to ESPN Stats & Information. In terms of pure need, re-signing cornerback Davon House after he was cut by the Jaguars qualifies as significant given how badly the pass defense struggled last season.

Most significant loss: T.J. Lang. Eddie Lacy. Micah Hyde. Julius Peppers. Take your pick. The losses outweigh the gains so far. They have no clear-cut replacement for Lang, who signed with the Lions after the Packers didn’t even come close with their offer. After Lacy signed with the Seahawks, it left Ty Montgomery as the only experienced running back. Hyde, who signed with the Bills, was the biggest playmaker down the stretch last season in a secondary that lacked big plays. And Peppers ranked second on the team in sacks to Nick Perry, who was re-signed.

Player they should have signed: Lang. The Packers talk often about retaining their own, but not only did they let Lang go, they watched him sign with a division rival. In seven months, they moved on from their two Pro Bowl guards yet will have to deal with each of them two times a year, with Lang in Detroit and Josh Sitton in Chicago. What’s more, the fact that the Packers weren’t even in the same ballpark as the market value for Lang probably won’t sit well with players in the locker room. Lang battled through injuries yet didn’t get rewarded for it by his own team.

What’s next: Any one of these veteran running backs -- Adrian Peterson, Jamaal Charles, Latavius Murray, LeGarrette Blount -- would be a wise signing for the right price. And it’s not too late. The running back market is still rich with talent. Sure, there’s significant risk with any or all of those backs, but it would be a mistake simply to rely on the draft to bolster their running game. Without a veteran back, they run the risk of having little or no consistent run game again next season. As much promise as Montgomery showed last season after moving from receiver, he’s still going to need help.

Overall grade: C-minus. Here’s the biggest issue: The two major holes on this team -- running back and cornerback -- remain largely unchanged. House was a decent pickup, but it should only be a start for a defense that ranked 31st in the NFL in passing yards allowed last season. One of the biggest mistakes a team can make is overvaluing its own talent, so the Packers had better make sure they cover for Damarious Randall, Quinten Rollins and LaDarius Gunter if the trio of young cornerbacks can't make significant strides this season.