Most significant signing: I'm going to amend this here and, for the purposes of the Lions, turn this into the most significant transaction. The biggest move for Detroit was trading for former Baltimore defensive lineman Haloti Ngata. Detroit had to make a big move to make up for the loss of Ndamukong Suh -- and later, Nick Fairley -- and the Lions traded away two draft picks that could have provided something in the future, in order to help the present of the franchise. The 31-year-old Ngata is considered one of the best linemen in the game, and even if his game is in the beginning of a decline, the Lions should be able to get a good year or two out of him. He's in the final season of his contract and will count $8.5 million against the cap unless Detroit signs him to an extension, which Ngata is open to.
Most significant loss: There is no other answer here than Suh. The Lions had expressed confidence for over a year that Suh would remain with the Lions, but Miami's massive contract numbers were too much for Detroit to reasonably put up and still be able to field a competitive team over the next five seasons. So the Lions had to let Suh leave and his loss will be felt throughout the team's defense, even with the acquisition of Ngata. Suh played an astronomical number of snaps for a defensive tackle last season (81 percent), was durable and dependable on the field and was one of the main cogs Detroit's defense was built around. It will be interesting to see how teams devise a game plan for the Detroit defense now that there isn't the constant need for a double-team on Suh every play. Expect Ezekiel Ansah to attract a lot of the attention Suh once received.
Biggest surprise: The trade for Ngata, covered above, was the biggest and only surprise for Detroit through the first week of free agency. Losing Suh was known before the new league year began, and the team never seemed completely sold on retaining Fairley. The move to sign tackle Tyrunn Walker -- the team's only outside free agent signing so far -- was not a splashy one, but a pickup that could end up being a strong one for the Lions. Detroit still needs to fill some holes in free agency, but maybe the biggest surprise is that the franchise didn't make many moves at all after losing Suh.
What's next: The Lions had guard Justin Blalock in for a visit late last week, and depending on what he does, that's going to be one area handled in free agency -- either by signing Blalock or re-signing Rob Sims. There are a couple of other options Detroit could pursue at guard, but at this point those are the two most likely. Cornerback is another spot the Lions need to fill, and don't be surprised if Rashean Mathis returns again with a thinning market. Guard and cornerback are the two major spots Detroit needs to fill with veterans at this point.