The Dallas Cowboys may have lost their starting running back DeMarco Murray to the Philadelphia Eagles, but they're still the reigning NFC East champions. The Cowboys have to improve their defense and build depth at running back.

Here are five free agents the Cowboys could consider signing this offseason.

1. Greg Hardy

The best NFL free agents have been signing with teams in bunches ever since the free agent period began on March 11. Defensive end Greg Hardy is arguably the best player remaining on the market. Hardy missed almost all of last season because of off the field issues, but he's had 27 sacks in his last 32 games. Hardy will cost a pretty penny, but this 26-year-old defensive end could become a franchise player for the Cowboys for a long time.

2. Knowshon Moreno

With Murray now an Eagle, the Cowboys have to strengthen their running game. Fortunately for them, this upcoming draft is running back heavy. If the Cowboys want to get a quality running back for a cheap price, then Knowshon Moreno could be their guy. Moreno missed almost all of last season, so his value is lower now than ever for a short term contract. In 2013 Moreno ran for 1,038 yards, 10 touchdowns and helped the Denver Broncos get to the Super Bowl. The Cowboys could attempt a small one or two year deal here with no real risk at all. If they don't like what they see, a preseason cut easily could be made.

3. Bernard Pollard

Football in general is a tough sport. Bernard Pollard isn't the greatest cover safety, but he is a very physical player who can make a difference. Pollard is a multidimensional strong safety who rushes the quarterback, tackles running backs and makes plays in the secondary. He can do what Brandon Browner did for the New England Patriots last season -- make the Cowboys a more physical team. Injuries are a concern with Pollard, but he's a risk that could pay off. Ask the Baltimore Ravens, who won the Super Bowl with him.

4. Vince Wilfork

It would be pretty weird seeing Vince Wilfork on a different team other than the Patriots, where he's played his entire career. He may be 33 years old, but Wilfork is still one of the best run stoppers in the NFL today. With Murray on the Cowboys schedule twice year now, he could be a good addition. Wilfork is a also a two time Super Bowl champion, and a great leader. Next season the Cowboys and Patriots will play each other. Wouldn't that be fun to watch?

5. Dwayne Bowe

There's a lot of notable wide receivers still unsigned, like Reggie Wayne, Wes Welker, Michael Crabtree, Nate Washington and Hakeem Nicks. Even Brandon Lloyd. The Cowboys could give former Kansas City Chief Dwayne Bowe a chance to succeed in their successful passing offense. Bowe has recorded more than 1,000 receiving yards in a season three times, and he did lead the NFL in receiving touchdowns in 2010. The Chiefs decided to part ways with Bowe, in favor of Jeremy Maclin. Maybe Bowe can find a rebirth in Dallas with Tony Romo throwing him the football. The Cowboys also have to have an insurance plan if Dez Bryant leaves next season as a free agent.

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