Cleveland Browns select Danny Shelton No. 12 in 2015 NFL draft

How do you fix the NFL's worst run defense? The Cleveland Browns are hoping the answer comes from adding 339 pounds of beef in Washington DT Danny Shelton. Shy of Jameis Winston or Marcus Mariota inexplicably falling into their laps, the Browns could not have asked more of the Round 1 board than to leave them a choice between Shelton and WR DeVante Parker, who would have filled another need.

However, the porous run defense had to drive coach Mike Pettine nuts last season, so the top priority became shoring up his team's front. Shelton is absolutely massive. He can hold up against multiple blockers, yet probably does his best work lined up directly over center. Shelton's combine 40 time (5.64 seconds) was atrocious, but he's not chasing anyone down long distance anyway. In a tight window along the line, he moves with surprising ease for his size. The Browns' defense just got tougher.

• 2015 NFL draft grades: Pick-by-pick analysis and scouting reports

Strengths: Shelton's a big man who's very hard to move when he's on point with his leverage. He plays two-gap nose tackle and one-tech shade primarily, but he could be used effectively all the way out to the end position, depending on scheme. Shelton's most startling attribute is his speed and agility in short spaces—he'll break off blocks at the line and tear after a running back or screen pass receiver and meet him at the sideline. He has gap-shooting capabilities, especially when he times holes in slide protection. He's a true three-down tackle—versatile and effective enough to avoid being rotated out—and his combination of power and athleticism makes him an asset in just about any scheme.

Weaknesses: Blockers who engage Shelton can do so because he fails to consistently use rip and swim moves to get free. He tends to wrestle and dance too much as opposed to using his hands to push through a block. Six of his nine sacks last season came against sub-par competition—Hawaii and Eastern Washington—and he probably won't put up those kinds of numbers in the NFL. As his snap counts increase, he will play higher off the ball and start to lose leverage. Weight has been an issue at times, and he ran a 5.64 40-yard dash with a 1.9 10-yard split at the scouting combine (slowest 10-yard split of any defensive lineman), though he plays faster than that. Gets so involved in pursuit at times that he'll blow assignments up the middle.

Player comparison: Vince Wilfork

Grade: A-minus

GALLERY: SCENES FROM THE NFL DRAFT

2015 NFL Draft in Pictures

The stage prior to the start of the first round of the 2015 NFL Draft at the Auditorium Theatre of Roosevelt University in Chicago.

Jameis Winston takes the call from the Tampa Bay Buccaneers, who made him the first pick.

Tampa Bay Buccaneers fans react after their team drafted former Florida State quarterback Jameis Winston with the first overall pick during the NFL draft party in Tampa, Fla.

Jameis Winston posed for SI in his new team's jersey after he was taken No. 1.

Marcus Mariota at his draft party in Honolulu.

Washington defensive lineman Danny Shelton picks up NFL commissioner Roger Goodell as he celebrates after being selected by the Cleveland Browns as the 12th pick.

Fans cheer after Kevin White of the West Virginia Mountaineers was picked seventh by the Chicago Bears.

Bears fans cheer Chicago's selection of Kevin White of West Virginia Mountaineers.

Dante Fowler with commissioner Roger Goodell after being drafted by the Jacksonville Jaguars.

Stanford offensive lineman Andrus Peat, right, talks to Deion Sanders after being selected by the New Orleans Saints as the 13th pick in the first round.

Green Bay Packers fans cheer during the first round of the draft.

A look at some of the NFL team representatives at the draft.

Kentucky linebacker Bud Dupree celebrates after being selected by the Pittsburgh Steelers as the 22nd pick in the first round.

Tampa Bay Buccaneers fans Keith Kunzig and David Miller are excited to have traveled from Florida to be at the first round of the 2015 NFL Draft.

Shane Ray checks out his threads.

Leonard Williams is interviewed outside the draft venue before being taken by the New York Jets.

Jameis Winston waiting for the call.

The scene inside the Jameis Winston draft gathering.

Marcus Mariotta in Hawaii before the first round began.

Two Patriots fans in Chicago.

Buffalo Bills Hall of Fame quarterback Jim Kelly arriving at the NFL Draft.

Chicago mounted police before the first round commenced.

Dante Fowler's shoes on draft night.

Chicago welcomed the NFL Draft with open arms.

The view from outside Roosevelt University Auditorium Theatre.

NFL prospect Trae Waynes of Michigan State talks to pediatric patient Alec Cabacungan while doing a mock interview during the NFL PLAY 60 activities at Shriners Hospital for Children on Thursday, April 30 in Chicago.