PHILADELPHIA (973espn.com) - Transpose 21 with 12 and change the pony with a tiger and you might have the storyline of the Eagles' offseason.

Rewind to last year and you might remember Doug Pederson taking a long look at what it would look like to have Darren Sproles and Donnel Pumphrey on the field at the same time. The formation was called '21 pony' and without pads, it sure looked like it could be a matchup nightmare for the linebackers and safeties around the league.

When the pads come on, however, someone has to block and by August, '21 pony' was a dead issue as it became clear the undersized Pumphrey wasn't going to be able to contribute as a rookie.

Ultimately, Pumphrey was essentially redshirted and will be fighting for his roster life this spring and summer.

Dallas Goedert, the Eagles' second-round pick out of South Dakota State, doesn't have to worry about things like roster spots but already the hype has started about the potential matchup nightmare of having two tight ends who are too fast for linebackers and two big for safeties to handle in the passing game.

And you can bet you'll hear a lot about Pederson and new offensive coordinator Mike Groh calling for 12 personnel this spring to get Zach Ertz and Goedert on the field at the same time.

“It creates matchups," Pederson said. "If he’s an athletic guy like a Zach Ertz, we can move him around, we can spread him out, he’s good in space, he understands spatial awareness. He’s great in man coverage because he can separate at the top of the route. Those become big bodies on smaller bodies.”

There are two ways to think about this and some subscribe to the theory that the evolution of the league points to more and more spread concepts while others believe the pendulum theory always wins out in the end in the NFL.

In this case the latter means if you use two detached tight ends all the time, opposing defensive coordinators are likely to use the overload blitz to take aim at the quarterback and if the most important player on the field is taking a beating with two detached tight ends on the field, the 'detached-tiger formation'  is going to be put on the same shelf as '21 pony.'

Last season the backup to Ertz in the detached role was the triggerman of the "Philly Special," Trey Burton, and remember, Burton was often billed as a "matchup nightmare" as well due to his athleticism and movement skills.

Yet, Burton only played in 27 percent of the snaps in the 2017 season.

If you take a deeper dive into that, it includes two games where Ertz was hurt, against Denver on Nov. 5 when Burton played in 68 percent of the reps, and against the Los Angeles Rams on Dec. 10 when Burton toiled 53 percent of the time, as well as the meaningless Week 17 finale against Dallas where Ertz made a cameo and Burton had a workload that reached 47 percent.

Take those three games out and the move TE behind Ertz played about 20 percent of the time or one in every five offensive snaps.

Some will counter with Goedert getting Brent Celek's work but how many times did you see the veteran Celek detached last season?

Goedert was not asked to block much at South Dakota State and that will change some at the pro level as it did with Ertz, who has worked tirelessly to improve his blocking, which remains the weak point of his skill set.

The good news is at 6-foot-5 and 260, Goedert at least has the frame to be a better blocker than Burton ever was but mismatches go both ways on the football field.

While Pederson ponders what LBs and safeties are going to so with two rangy, athletic tight ends on the field at the same time, opposing defensive coordinators are going to see a quarterback with a bulky knee brace behind a lesser layer of protection.

"With any player, not even talking about the level of playbook, with any player coming in there's going to be some technique refinement," Eagles personnel chief Joe Douglas said when asked about Goesert's blocking by 973espn.com. "So we're going to help him there and feel that [Tight Ends coach] Justin Peelle is going to do a great job helping him with technique at the point of attack as a blocker."

-John McMullen covers the Eagles and the NFL for 973espn.com. You can reach him at jmcmullen44@gmail.com or on Twitter @JFMcMullen