5 most improved teams after 1st wave of free agency

Winning in March doesn't necessarily correlate to winning in September, but it's hard not to feel optimistic after a triumphant free agency.

These five teams emerged from the opening stages of free agency with the most improved rosters - at least on paper:

Oakland Raiders

The Raiders made splashes early and often, ensuring their final season in Oakland will be one to remember. Head coach Jon Gruden and new general manager Mike Mayock teamed up to land Antonio Brown, arguably the best receiver in football, and only surrendered a pair of mid-round draft picks to do so. They also made much-needed upgrades to the offensive line and defensive secondary.

Notable additions:

*Re-signed with team

Cleveland Browns

General manager John Dorsey did the unthinkable, prying superstar receiver Odell Beckham Jr. from the New York Giants without giving up multiple first-round picks. The Browns traded away standout guard Kevin Zeitler but have enough depth along the offensive line to handle the loss. Cleveland also beefed up its defensive front and suddenly appears poised to overtake its AFC North rivals after years in the divisional cellar.

Notable additions:

*Re-signed with team

Buffalo Bills

The Bills had a sneaky-good free agency, addressing their top needs without compromising future financial flexibility. Buffalo may not be ready to challenge the AFC powerhouses quite yet, but it improved the talent level around second-year quarterback Josh Allen. The Bills also kept the bulk of last year's No. 2-ranked defense intact.

Notable additions:

Green Bay Packers

Cheeseheads rejoiced as the Packers finally bucked their frustrating trend of passivity in free agency. Green Bay shored up its defense with three new starters and added depth to an offensive line that's been ravaged by injuries in recent seasons. There's still time to add offensive weapons for Aaron Rodgers, whether it's through free agency, the trade market, or the draft.

Notable additions:

New York Jets

The Jets entered free agency with loads of cap space and used it to land Le'Veon Bell and C.J. Mosley, two of the biggest fish in the pool. They also acquired offensive lineman Kelechi Osemele, who could turn out to be a steal if he's over the injuries that hampered him last year. New York lost a verbal commitment from Minnesota Vikings linebacker Anthony Barr but still came away with a strong haul.

Notable additions:

*Re-signed with team