The Eagles are currently on the search for their next offensive coordinator after parting ways with Kevin Patullo following his first year in the role. They’ve spread their search pretty far and wide with over nine interviews requested so far, but it seems their reach fell just short in one rival city. According to Jeremy Fowler of ESPN, Philadelphia requested to interview Cowboys offensive coordinator Klayton Adams for the same role with the Eagles but saw their request blocked by Dallas. 
It’s true that teams are allowed to block other teams from hiring away coaches under contract with them in what would be a lateral move elsewhere. It’s fairly common and fully justifiable. There is a slight change in thinking sometimes, though, when it comes to the responsibility of calling plays. While Cowboys head coach Brian Schottenheimer and Eagles head coach Nick Sirianni both come from offensive backgrounds, Schottenheimer calls the offensive plays in Dallas, while Sirianni trusts that role to his offensive coordinator.
Typically, if an offensive coordinator currently serves under a head coach who calls plays for the offense, it is not necessarily considered a lateral move to interview for a job elsewhere in which they would have the opportunity to call plays. The organization usually allows for interviews like that to occur. For instance, Bengals offensive coordinator Dan Pitcher (under play-calling head coach Zac Taylor) was permitted to interview with the Buccaneers, where defensive-minded Todd Bowles serves as head coach. In Tennessee, Packers offensive coordinator Adam Stenavich (under play-calling head coach Matt LaFleur) was permitted to interview with the Titans, under defensive-minded Robert Saleh.
The Eagles also requested interviews with current coordinators on the Colts and Bears, knowing that Shane Steichen and Ben Johnson both call the offensive plays for their respective teams. Both requests were reportedly granted, so Philadelphia should soon be able to schedule their eighth and ninth interviews for the offensive coordinator position. Of all the teams not replacing head coaches who saw requests to interview their offensive coordinator who currently does not get to call plays, the Cowboys are the only team to have blocked the requested interview.
Now, this could be plainly due to a fierce divisional rivalry, with strategy provoking a “hands off” response. The other possibility is that the Cowboys truly value Adams and what he brings to an offense that finished with the second-most yards gained in the NFL and the seventh-most points scored. Surely, at some point in his career, Adams will want to earn his wings as an offensive coordinator at some point with the opportunity to call plays, but as someone who has spent most of his career coaching tight ends and offensive line and has never called plays before, he may not quite be ready for that role.
So, for now, Adams will continue to work in his role for the Cowboys with Schottenheimer calling plays for one of the league’s most potent offenses. The Eagles will have to continue searching elsewhere for their next offensive coordinator and play caller.