Are Andre Dillard and Darius Slay who the Eagles think they are? It’s the biggest question of the 2020 season. | David Murphy

There are all kinds of questions that will play a role in determining just how good the 2020 Eagles can be.

Will Carson Wentz finally return to the MVP form we saw out of him in 2017? Will Jalen Reagor make an impact as a rookie? Will the defensive line be transformed by the additions of Javon Hargrave (from free agency) and Malik Jackson (from injured reserve)?

But if you look past Wentz, there aren’t two players more critical to their respective units than Andre Dillard and Darius Slay. And there aren’t two questions more pressing than as follows:

(1) Is Darius Slay as good as he used to be?

(2) Is Andre Dillard any good at all?

If the answer to either is anything less than a wholehearted “yessir,” the Eagles are going to have a host of problems for which there might not be any fix. For all the grief Howie Roseman has taken for last week’s curious draft, his post-Super Bowl tenure as general manager is going to be defined by a series of moves that have already been made.

Set aside for a moment that pesky little issue of scouting the draft. It’s possible to give Roseman a pass on the Eagles’ failure to develop a young core of players to relieve some of the pressure on Wentz.

There’s a long list of coaches and executives who may deserve some level of blame for the state of the Eagles’ depth chart the last couple of seasons. Chip Kelly, Joe Douglas, Jeffrey Lurie, perhaps Doug Pederson -- we don’t have a great idea what specific role any of them played in any specific transaction, beyond whatever the media guide says about their job title.

What we do know is that the current situation at cornerback and left tackle is the result of the sort of higher-level decision-making that is a general manager’s sole purview.

Take Slay, for example. On a micro level, there was little downside to the deal the Eagles’ struck with the Lions. History says they were highly unlikely to find a player with as much immediate upside as Slay with the third-round pick that they traded to Detroit. The fifth-rounder they kicked in is barely worth mentioning. The Eagles drafted a quarterback there last year and nobody even had a conniption.

Even if the trade for Slay doesn’t turn out to a clear-cut win, it’s going to be difficult for it to go down on a loss.

It’s a much different story when you look at the picture in total. The Eagles might not need Slay to be a shutdown corner to be worth the price they paid for him, but they almost certainly will need him to be something close to that in order to validate the rest of their offseason maneuvering.

The defense that Roseman, Pederson, and Jim Schwartz are constructing is contingent on two things: a smothering pass rush, and an All-Pro cover corner who can handle any assignment by himself. If Schwartz has that, it is reasonable to believe that he can make the rest of it work.

In theory, the upgrade from Ronald Darby to Slay will be greater than the downgrade from Malcolm Jenkins to Jalen Mills or Will Parks or K’Von Wallace, plus whatever difference exists between Mills at corner and whoever ends up starting opposite Slay.

But all of those things are contingent on Slay’s being something greater than a glorified version of Darby in 2017. Last year, he wasn’t even that. Pro Football Focus rated him as one of the worst starting cover corners in the NFL.

There’s plenty of reason to think that 2019 was an anomaly. Slay was unhappy in Detroit, and he’d spent the previous four years as one of the best-rated corners in the NFL. At 29 years old, he should have plenty of tread left on the tire. But there is some uncertainty here, especially when you consider that the best the Lions could do on the trade market was the price the Eagles ended up paying.

It’s a similar story at tackle, where Lane Johnson is the only player on the team with more than 350 career snaps at the position. The Eagles know how important the blind side is. Since 1997, all but one season has featured either Tra Thomas or Jason Peters at left tackle. The one exception was 2012, when Peters was injured and the Eagles went 4-12.

When they traded up to draft Dillard last spring, they envisioned him as the man who would continue that line of succession. But his rookie season was a concern. He graded out well in two of his four starts at left tackle, but it is hard to overlook his disastrous performance at right tackle against the Seahawks and the Eagles’ reluctance to go back to him afterward.

While Dillard compared the switch to right tackle to being asked to write with his non-dominant hand, plenty of rookies have been asked to make the transition, including several who were in his draft cohort.

At minimum, it was a bad look, and reason to wonder whether he will be able to handle the pressure of being the only option to protect Wentz’s blindside.

The Eagles have not drafted a cornerback since selecting Avonte Maddox, Rasul Douglas, and Sidney Jones in 2017 and 2018. Dillard is the only tackle they have taken in the first four rounds since Johnson in 2013.

If Slay and Dillard end up matching the production the Eagles envisioned when they acquired them, there’s a chance they’ll have the most talented team of the Pederson-Roseman era. But if they don’t, there isn’t much in the way of backup.

Slay and Dillard aren’t just keys. They’re prerequisites.