The most popular sports league in the United States is about to start up again. After waiting six long months, the 2015 NFL preseason is just a week and a half away. Although preseason games don't count, they do matter.

Here are 10 things to watch for this preseason.

1. Tim Tebow

The Philadelphia Eagles stunned many by trading away Nick Foles for Sam Bradford and later signing Tim Tebow. Mark Sanchez is still on the Eagles roster, but Tebow will definitely get some snaps. Maybe Tebow is better equipped to run the Chip Kelly offense because of his mobility. This could be his last chance.

2. Cowboys Backs

Joseph Randle is now the go-to guy in Dallas because DeMarco Murray is in Philadelphia. Darren McFadden will get some playing as well this August. The Cowboys have an elite offensive line, but they still need an effective running back carrying the ball. Now is the time to practice new plays.

3. Patriots Secondary

The defending Super Bowl champions lost quite a bit this offseason. They re-signed safety Devin McCourty, but they lost two valuable corners in Darrelle Revis and Brandon Browner. Can Bill Belichick work his magic with this secondary, or is it just too much to overcome? Last season the Patriots pass defense ranked 17th overall even with Revis and Browner.

4. Jimmy Garoppolo

Speaking of the Patriots, they don't have Tom Brady for the first four games of the season because of "deflategate." If Brady's suspension holds up, Jimmy Garoppolo will be the starter. Garoppolo has never started an NFL game in his young career, but he may very well get the start in Week 1 against the Steelers.

5. RG3

It wasn't that long ago that Robert Griffin III won Offensive Rookie of the Year. Unfortunately, it's been downhill ever since. Controversy with coaches, injuries and inaccurate passes have highlighted the last two years with the Washington Redskins. Griffin is under a lot of pressure this season, and he has been battling a few injuries as well.

6. Colts Offensive Additions

The Colts may very well of had the best offseason of any team in the league. They added future Hall of Fame wide receiver Andre Johnson and running back Frank Gore. Andrew Luck now has two more weapons to utilize to his advantage this year.

7. Broncos New Offense

As long as Peyton Manning is in town, he runs the show. However, the Broncos are going to look a little bit different this season. C.J. Anderson will get a lot more carries, and the Broncos now have a new head coach in Gary Kubiak. It will be interesting to see the Broncos without Julius Thomas as well.

8. Steelers Defense

The days of the "Steel Curtain" are in the past. This Pittsburgh Steelers squad is all about offense. Dick LeBeau is no longer the defensive coordinator in Pittsburgh, and the Steelers defense has ranked 13th and 18th overall the last two seasons. If the Steelers are going to win ring No. 7, the defense has to improve dramatically.

9. Carson Palmer

It was a disappointing end for the Arizona Cardinals last season as Carson Palmer only played six games before tearing his ACL. Palmer was 6-0 as the Cardinals quarterbacks last season with 11 touchdowns and just three interceptions. Can Palmer return as a solid quarterback or will injuries again halt his performance?

10. Jimmy Graham

The Seattle Seahawks will always go as far as their defense takes them, but the addition of tight end Jimmy Graham from the New Orleans Saints was a big one. Graham is one of the best tight ends in the league today, and he should fit in nicely catching passes from Russell Wilson. Adding an elite end zone threat never hurts.

Follow Damon Salvadore on Twitter @DamonSalvadore1