Ranking the most improved NFL teams

— -- Unrestricted free agency comes to a halt Tuesday, as UFAs turn into street free agents, meaning they no longer count against a team's ability to get a compensatory pick in 2017.

While there will be signings and possible trades from now until training camp and beyond, a clear picture has emerged in determining which teams improved the most during the offseason. Fifteen of the 20 teams that didn't make the playoffs last year had bad defenses, surrendering 24.2 points per game or more.

Most of the efforts of the non-playoff teams went into signing or drafting defenders. Most playoff teams, however, didn't invest big money into defensive acquisitions. The exceptions were the  Washington Redskins, who signed cornerback Josh Norman for $15 million per year, and the Arizona Cardinals, who traded for pass-rusher  Chandler Jones, who has one year left on his deal at $7.8 million. All the other deals for defenders on teams that made the playoffs came at bargain prices.

Bottom line, the teams that improved on defense have the best chance of winning the offseason. Here are the six teams that improved the most, in order:

1.  <a href="http://espn.go.com/nfl/team/_/name/jax/jacksonville-jaguars">Jacksonville Jaguars</a>

Caldwell said last year that you can't necessarily rely on rookies to make a big improvement. That's why the signing of Prince Amukamara to a one-year contract helps. He takes pressure off Ramsey and buys time for the rookie to develop. The Jags gave up 28 points per game last year. If all works out, they should shave four points per game off that total.

A bonus for Jacksonville was adding halfback Chris Ivory. They now have a running attack that should help the defense.

2.  <a href="http://espn.go.com/nfl/team/_/name/nyg/new-york-giants">New York Giants</a>

New signing  Olivier Vernon and Jason Pierre-Paul, who's back for a full season, will provide the pass rush. Janoris Jenkins, Dominique Rodgers-Cromartie and first-round pick Eli Apple offer about as talented a three-cornerback coverage group as you can find in the league. Damon Harrison will be the run-stuffer. Keenan Robinson and Kelvin Sheppard add more depth at linebacker.

Figuring new coach Ben McAdoo should get 25 to 26 points per game out of the Eli Manning-led offense, all the Giants need to do is cut three or four points per game off the defense to have a winning record.

3.  <a href="http://espn.go.com/nfl/team/_/name/ten/tennessee-titans">Tennessee Titans</a>

The Philadelphia Eagles gave him DeMarco Murray, and then halfback Derrick Henry fell to him in the second round. Center Ben Jones and first-round right tackle Jack Conklin fill out a talented offensive line that plans to play smash-mouth football.The Titans took six defensive players in the draft and added four more in free agency.

Maybe they need next year's draft -- when they'll have two first-round picks -- to make a big jump on defense, but they have done enough to think about a three- or four-game jump in the standings.

4.  <a href="http://espn.go.com/nfl/team/_/name/oak/oakland-raiders">Oakland Raiders</a>

The secondary now has cornerback Sean Smith and safeties Reggie Nelson and Karl Joseph. Bruce Irvin adds speed off the edge, and the re-signing of Aldon Smith should add a pass rush down the stretch. At 7-9, the Raiders were a team on the rise last season. This year's moves could put them in playoff contention.

5.  <a href="http://espn.go.com/nfl/team/_/name/tb/tampa-bay-buccaneers">Tampa Bay Buccaneers</a>

This offseason, Licht took the Noah's Ark approach and helped a defense that surrendered 26.1 points per game. He added two pass-rushers in  Robert Ayers and Noah Spence. He added two cornerbacks in  Brent Grimes and Vernon Hargreaves III. Linebacker Daryl Smith will help the young linebacking corps.

The Bucs had three studs on defense last season -- defensive tackle Gerald McCoy and linebackers Lavonte David and Kwon Alexander. One more solid draft should put this defense over the top.

6.  <a href="http://espn.go.com/nfl/team/_/name/chi/chicago-bears">Chicago Bears</a>

Coaches John Fox and Vic Fangio cut 2.8 points per game off a defense that allowed 27.6 before they arrived. Now, the Bears are assembling talent to shave more points off their average.