The 2015 NFL regular season doesn't officially begin until September, but offseason grades are flying across the web. NFL offseason winners and losers are being debated everywhere because of huge trades, free agent signings and draft selections.

Unfortunately for some teams, they didn't have a very good offseason this year.

Here are five teams who had a bad offseason.

1. San Francisco 49ers

There's no debate on this one. The 49ers defense is going to look very different next season because of so many departures from the roster. Notable players such as Patrick Willis, Bubba Ventrone, Chris Borland and Justin Smith all retired. Michael Crabtree also left the team via free agency to sign with the Oakland Raiders. Colin Kaepernick now has a huge responsibility next season with less reliable targets and an average defense. Oh, and let's not forget Jim Harbaugh (who was 44-19-1 as the 49ers coach) left the 49ers to coach at Michigan.

2. New England Patriots

Thank goodness the Patriots won the Super Bowl last year. Entering next season, things will be very different. The Patriots will be without their best defensive tackle Vince Wilfork, who helped the team win two Super Bowls with his great run blocking abilities. The Patriots secondary was also depleted. Darrelle Revis is back with the New York Jets and Brandon Browner is now a member of the New Orleans Saints. On top of three great defensive players now off the roster, Tom Brady has been suspended four games for "deflategate." Bill Belichick has a tough task ahead of him.

3. Denver Broncos

The Broncos will have a new head coach (Gary Kubiak) next season, despite the fact that John Fox led the team to a Super Bowl appearance just one year ago. Peyton Manning is still one of the best quarterbacks in the game, but he isn't getting any younger, and he is recovering from a torn quad injury. Franchise tagging Demaryius Thomas was the correct decision, but he may leave after next season. Tight end Julius Thomas, who has 24 touchdowns the last two seasons, is now a member of the Jacksonville Jaguars. Defensively, the Broncos also lost their best defensive tackle Terrance "Pot Roast" Knighton to the Washington Redskins.

4. Philadelphia Eagles

The Eagles and Chip Kelly took a lot of risks this offseason, and it didn't really improve their roster. Signing cornerback Byron Maxwell was a huge upgrade to the secondary, but the offense took a big hit. The Eagles traded away Nick Foles to the St. Louis Rams for Sam Bradford, who has torn his ACL the last two seasons. The Eagles also traded away star running back LeSean McCoy for a linebacker who didn't even play last season. DeMarco Murray had a terrific 2014 season, but he's not as versatile as McCoy. The Eagles also couldn't swindle a trade with the Tennessee Titans to get Marcus Mariota. So, now it's up to Mark Sanchez, an injury-prone Bradford or Tim Tebow to lead the way in Philadelphia.

5. San Diego Chargers

The Chargers have missed the playoffs four of the last five seasons, mostly due to the fact that they haven't had a reliable running back. The Chargers still don't have a proven running back on the roster to help aid Philip Rivers. The Chargers also didn't do much to improve their defensive line that ranked 26th in rushing yards against last season. As for Rivers, he has just one year remaining on his contract until the Chargers either lose him or spend a lot of guaranteed money.

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