Looking to build off their most successful season in half a decade, the Dallas Cowboys endured significant losses and gains this offseason. Dallas finished with an impressive 12-4 record and took back the NFC East, but allowed last year’s top running back DeMarco Murray to head to Philadelphia, and watched a key contributor on one of the best offensive lines in the game, right tackle Jermy Parnell, head to Jacksonville.

Owner and general manager Jerry Jones also made some upgrades, specifically addressing the pass rush with a one-year, $11.3 million deal with defensive end Greg Hardy, and added some depth at linebacker in Jasper Brinley and Andrew Gachkar with only $4 million guaranteed to both.

And now, rather than put themselves in a deep salary cap hole by overspending in free agency, it appears Dallas will opt to further improve its pass rush, bolster a secondary that ranked No. 26 in the league last year, and find a suitable long-term replacement for Murray with its seven selections in the upcoming 2015 NFL draft.

The Cowboys surrendered 251.9 passing yards per game in 2014, and mustered 28 total sacks, the fourth-lowest mark in the league. The addition of Hardy will go a long way to improve the latter, but defensive back is still a major concern heading into the draft, especially amidst the current contract situation with veteran cornerback Brandon Carr and last season’s passes defended leader Sterling Moore moving on to Tampa Bay.

In terms of Carr, the Cowboys believe he has vastly underperformed since signing a five-year, $50 million contract, and now the team is looking to scale back his pay. Carr and his agent, Ben Dogra, are steadfastly opposed to a pay cut, and team vice president Stephen Jones’ recent comments suggest the Cowboys will find a way to keep Carr on the roster. Cutting Carr seems like a drastic measure; especially given the $12.1 million dead cap hit he would register if Dallas decides to part ways.

Former first-round pick Morris Claiborne will also be a free agent after next season.

Dallas could gain a good amount of leverage over Carr and Claiborne if they can find a star defensive back in the draft, running from April 30 to May 2, with one pick apiece in the first five rounds and two in the seventh. The Cowboys don’t have a selection in the sixth round after completing a trade with the Baltimore Ravens for linebacker Rolando McClain.

Here are several prospects Jerry Jones should seriously consider over the three-day draft process, specifically at defensive end, running back, cornerback and even wide receiver.

Alvin Dupree, DE, Kentucky

There’s been plenty of speculation of Dallas burning its No. 27 overall pick on a running back like either Wisconsin’s Melvin Gordon or Georgia’s Toddy Gurley, the consensus two best rushers available. But a first round selection might be better used finding Hardy a young running mate. Hardy, however, will also be a free agent in 2016, as will last season’s sack leader and defensive end Jeremy Mincey.

That’s where Dupree comes in. He has both size and athleticism, using a 6-foot-4, 269-pound frame to provide an impressive performance at last month's combine. Dupree clocked in at 4.56 in the 40-yard dash and showed a 42-inch vertical leap. Over the last three years at Kentucky, Dupree put up at least 6.5 sacks and scouts feel there is still room for improvement.

Duke Johnson, RB, Miami

A gifted and powerful rusher, Johnson could step in right away behind the Cowboys frontline. He’ll also provide solid insurance for running back Darren McFadden, who’s struggled with injuries throughout his career, and rusher Joseph Randle, a free agent in 2016.

Gurley and Gordon could very well go in the first round, but even if they fell to the second round Dallas would be unlikely to snag either at No. 60 overall. The Cowboys clearly believe in their offensive line, and that most any running back can excel behind it. So in sticking with the front office's apparent thinking, using a second-round pick on a running back makes more sense than a first-rounder.

And it’s not like Johnson is a consolation prize either. He put up a blazing 1,652 rushing yards and 10 touchdowns, and showed some versatility with a career-best 38 receptions for 421 yards and three more touchdowns, earning All-ACC first-team honors last season. A poor injury history is a concern, but if Johnson dips past the third round he represents great value.

Ronald Darby, CB, Florida State

This year’s cornerback class goes fairly deep, with lots of quality prospects probably available in the third to fourth round. If Darby slips to the third round, the Cowboys could have a potential steal on their hands.

He started all 28 games the last two seasons, including the Seminoles 2013 undefeated national title run that was led by quarterback Jameis Winston, but also one of the more incredible defenses in college football in recent memory. As a sophomore he came up with 14 total tackles, four passes defended and two interceptions. He then improved his tackling with 43 total in 2014 and notched four more passes defended.

If Cowboy fans are worried about Darby’s size (5-foot-11, 193 pounds), a closer look at his blazing speed was second only to top cornerback prospect Trae Waynes at the combine.

Tony Lippett, WR, Michigan St.

The Cowboys used the franchise tag on Dez Bryant to not only keep him off the free agent market, but also to continue negotiations with arguably the best receiver in the NFL. Should those go south, Dallas could turn to a deep receiver class for a long-term solution.

Lippett is a versatile player, starting at both wide receiver and at times cornerback for the Spartans last season. He showed improvement every year in Lansing, and in his senior season totaled 1,198 yards and 11 touchdowns. Lippett didn’t have the best showing at the combine, but he bettered his 40-yard dash time to 4.57 seconds on his pro day, showing the type of work ethic and determination every NFL team desires in players. As a fourth-round selection, Lippett could enter next season as a huge target for quarterback Tony Romo on third down.