Oakland Raiders

Key Arrivals: Rodney Hudson (UFA), Dan Williams (FA), Lee Smith (UFA), Nate Allen (UFA), Roy Helu (UFA), Curtis Lofton (SFA), Trent Richardson (SFA)

Key Departures: Darren McFadden (UFA), Tyvon Branch (released), Chimdi Chekwa (UFA)

Two of the Raiders' main signings address their offensive and defensive lines: Rodney Hudson's signing should help the Raiders' offensive line, and Dan Williams' should help their defensive line. The Raiders ranked dead last in rushing yards per game at 77.5 yards per game, and Hudson should help with that. On the flip side, Williams' addition should help a Raiders' defensive line that ranked 22nd in rushing yards per game allowed but eighth in per-play yards allowed. Williams and defensive end Justin Tuck should make for a stout duo in defending the rush and the pass.

Along those same lines, the Raiders added a couple running backs in the wake of Maurice Jones-Drew's retirement and Darren McFadden's free agency signing with the Cowboys. Though Latavius Murray showed signs of breaking out late in the season, especially in their win over the Chiefs before he was sidelined with a concussion, Oakland looks to give him a dose of competition, signing Helu (formerly with Washington) and Richardson (formerly with Indianapolis).

Lee Smith's addition helps the Raiders mostly as a blocker after four seasons on the Bills, where he started 24 of 30 games in his previous two seasons.

Elsewhere on the defense, Oakland picked up a solid safety in Nate Allen, who rated positively in both pass coverage and run defense by Pro Football Focus, and linebacker Curtis Lofton. Lofton was a part of a pretty dreadful Saints defense last year, but he was a tackling machine with 144 combined tackles in 2014. The Raiders could use help at middle linebacker and Lofton should help there.

Overall, the Raiders might not have made the big free agency splash some might have thought, but they bolstered some weak points on their roster. With the draft rapidly approaching, you'd expect them to find other solutions to roster holes with the fourth overall pick in the first round and with high selections throughout the seven rounds.

San Diego Chargers

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Key Additions: **Orlando Franklin (UFA), Stevie Johnson (SFA), Patrick Robinson (UFA), Jacoby Jones (SFA)

Key Departures: Ryan Mathews (UFA), Eddie Royal (UFA), Shareece Wright (UFA), Marcus Gilchrist (UFA)

Orlando Franklin looks to be the biggest addition for the Chargers. Though injuries ravaged San Diego's running backs and interior linemen—San Diego started five different centers through the 2014 season—the Chargers' offense had serious problems getting their rushing offense going, ending up 31st in rushing yards per play. The Chargers can use Franklin at guard or right tackle, but lineman D.J. Fluker might be most comfortable in that position and Franklin was quite effective at guard, especially as the season went on.

San Diego signed released wide receiver Stevie Johnson after Eddie Royal left to join the Bears. Royal was a favorite target of Philip Rivers, and the Chargers hope Johnson can fill that role. Though Johnson hasn't been able to return to his three-year peak with the Bills from 2010 to 2012 in which he had three consecutive 1,000-yard receiving seasons, establishing chemistry and stability with Rivers could help him get back to better years than the one he had last year in San Francisco.

Patrick Robinson rated as the best cornerback on the Saints last year and should push Jason Verrett, who played very well for the Chargers as a rookie before having to be placed on the injured reserve with a shoulder injury. If nothing else, he looks to be a solid nickel corner who can be insurance in case of injury.

Ryan Mathews' departure isn't the biggest deal for the Chargers. Last year they hit some major speed bumps with injuries to their running back corps, but with Branden Oliver and Danny Woodhead back, they shouldn't miss much of a beat as Mathews heads to Philadelphia.

Kansas City Chiefs

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Key Additions**: Jeremy Maclin (UFA), Tyvon Branch (SFA), Paul Fanaika (UFA)

Key Departures: Rodney Hudson (UFA), Dwayne Bowe (released), Kurt Coleman (UFA), Anthony Fasano (released), Vance Walker (released)

The biggest addition in the AFC West was the signing of wide receiver Jeremy Maclin, formerly of the Eagles. The woeful Chiefs receiving squad that infamously struggled mightily trying to get a receiving touchdown should have far less trouble doing so in the 2015 season with the explosive Maclin. He was drafted under Chiefs Head Coach Andy Reid when he was with the Eagles, and in those years under Reid, Maclin racked up about 3,500 receiving yards and 26 touchdowns.

The other major move by the Chiefs was using their franchise tag on star outside linebacker Justin Houston. No controversy there. Kansas City will undoubtedly look to wrap up Houston on a long-term deal at another time, but for now, this was a no-brainer move.

As far as departures, center Rodney Hudson and safety Kurt Coleman are probably the biggest losses. Hudson rated out as the Chiefs' best lineman and his move across the division to the Raiders might sting a bit, and Coleman did well in pass coverage.

Bowe was released by the Chiefs, and Maclin's arrival will be a big impact. Fasano, who was also released by Kansas City, isn't the biggest loss with the emergence of athletic tight end Travis Kelce as one of the Chiefs' best receiving threats.

Denver Broncos

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Key Additions:** Owen Daniels (UFA), Vance Walker (SFA), Darian Stewart (UFA), Shelley Smith (SFA)

Key Departures: Orlando Franklin (UFA), Nate Irving (UFA), Terrance Knighton (UFA), Julius Thomas (UFA), Rahim Moore (UFA)

The Broncos made their biggest "offseason" move back in November when they completed a contract extension with Chris Harris Jr. to wrap up one of the league's best cornerbacks long-term (one could argue he was the best in the NFL last season). Their other big move was to use their franchise tag on Demaryius Thomas, the franchise's record-holder in single-season receiving yards and single-game receiving yards.

While their new additions didn't have the big-name recognition of past free agency splashes, they instead used the period to keep two of their best players on either side of the field in Harris and Demaryius Thomas.

Owen Daniels might be the player who knows Gary Kubiak's offensive schemes, and offers a diverse skill set as not only a receiver, but as someone who can block well in different situations. Keeping tight end Virgil Green a Bronco shows the team's trust in the young tight end who was a real difference-maker on the field last season, and the Broncos look to expand his role further in the passing game.

While the losses of Franklin and Knighton hurt in the trenches, the Broncos made two signings to shore up their depth there with young talent on the roster already. Walker adds depth to the line and was an effective player for the Chiefs last year in limited time, and already has experience playing in a 3-4 defense. Guard Shelley Smith has played for Kubiak before in his first two years in the league, so he brings a knowledge of the zone blocking scheme. Darian Stewart, who looks to be the new starter for the Broncos after Rahim Moore's departure, showed better tackling on the Ravens last year and rated positively in Pro Football Focus' advanced stats.