An outside linebacker on nearly half the teams in the NFL would play defensive end for most other teams, or might not even have the skill set to make that switch. Some 3-4 outside linebackers might struggle as a hand-on-the-ground lineman.
"When you stand up, everything changes," NFL Network analyst Mike Mayock said. "Think about it: You spent your whole life going forward, now I have some coach telling me to drop back, and some guys can and some guys can't."
The Eagles' plans require upgrading the pass rush when free-agency negotiations begin Saturday and during May's draft. The Birds finished No. 20 in the NFL with 37 sacks, and Trent Cole and Brandon Graham were trying to shift to new roles. Connor Barwin was the only natural 3-4 outside linebacker on the team last season.
The free-agent market does not appear to be especially deep in potential 3-4 pass rushers, although the benefit is that fewer players require a position switch. The top two were Washington's Brian Orakpo, who was given the franchise player tag, and Pittsburgh's Jason Worilds, who accepted the transition player tag.
Beyond them, there's no player who would present a clear upgrade over Cole, who Roseman said is "continuing to get better" in the 3-4 after spending the first nine seasons of his career at defensive end.
Among the intriguing options are Green Bay's Mike Neal (6-foot-3, 285) and Seattle's O'Brien Schofield (6-3, 242). Neal is a 26-year-old former second-round pick who was actually a 3-4 lineman before converting last season. He's versatile, although he has limited experience dropping into coverage. Schofield, also 26, played outside linebacker for Eagles defensive coordinator Bill Davis in Arizona. Both players have mostly been reserves in their careers.
The draft might be the better place to look. The top three pass rushers (South Carolina's Jadeveon Clowney, Buffalo's Khalil Mack, and UCLA's Anthony Barr) are all expected to be off the board by the time the Eagles pick at No. 22. The Eagles could have options late in the first round. For most of the prospects, Roseman must determine how well a player projects in the new role.
Auburn's Dee Ford (6-2, 252) fits the profile of a player who could switch, and said at February's scouting combine that he did not think a change would be an issue. Stanford's Trent Murphy (6-5, 250) played as a 3-4 rush linebacker in college and led the nation in sacks, and he even played defensive line at the Senior Bowl so teams could see him with his hand on the ground. Missouri's Kony Ealy (6-4, 273) is a talented prospect who might project more as a 4-3 defensive end.
Mayock said the "eye level" is a major difference between playing on the line and playing standing up. He has talked to players who have made the transition, such as Cole and Kansas City's Tamba Hali. Some like to see only the tackle in front of them from the line, while others prefer seeing the whole field from a stand-up position.
Many coaches would dispute a label as restrictive as a 3-4 defense or a 4-3 defense, considering most of the game is played with substitution packages. Kelly is one of them, and the Eagles' defensive schemes are based on the opponent's formation and personnel. But the players they look for have changed from the previous regime.
In the Eagles front office, some of Roseman's top deputies have backgrounds with the 3-4 defense. Vice president of player personnel Tom Gamble looked for 3-4 players when he was with the San Francisco 49ers. Senior adviser Tom Donahoe spent more than two decades with the Pittsburgh Steelers. Assistant director of player personnel Ed Marynowitz came from Alabama, where Nick Saban runs a 3-4 base defense.
They must be able to find players who can make the transition, because there are not as many college players like Murphy who play in a formation similar to the Eagles'.
"You have to keep your vision on the quarterback and be able to see everything as you're dropping," Murphy said. "A lot of the purely rush defensive ends don't have that experience."
Note. The NFL's "legal tampering" period for free agency begins Saturday at noon and extends until 4 p.m. Monday. The Eagles can negotiate with the agents of players, but they cannot speak to players, host visits, or reach contracts until Monday.