DeSean Jackson (right) celebrates an Eagles’ touchdown Monday night (Patrick Smith/Getty Images)

Coach Mike Shanahan said Tuesday that the Washington Redskins were not unprepared on defense for what they saw from the Philadelphia Eagles’ offense during Monday night’s season-opening defeat.

“There was only one play that we saw that we hadn’t practiced against,” Shanahan said at Redskins Park. “From that standpoint, I felt pretty good about that. There was only one play they ran offensively that was a surprise to me that I hadn’t seen before on tape.”

The Eagles’ uptempo offensive approach seemed to have the Redskins reeling, especially in the game’s early stages. Shanahan did acknowledge that mistakes were made.

“We had a couple mis-alignments with their unbalanced set,” Shanahan said. “I always put the responsibility on that on coaches, not on players. We had a few missed tackles. That has a lot to do with [running back LeSean] McCoy and [quarterback Michael] Vick and a couple of their great athletes they do have. But we did adjust. We did make a few adjustments and I was pleased with the way we came back in the second half, even though we fell short.”

Linebacker Ryan Kerrigan said the Redskins had a good plan on defense to deal with the problems presented by the Philadelphia offense.

“It’s little things and that’s what  was really disappointing about last night,” Kerrigan said. “We had a good game plan going in and they didn’t throw anything at us that we hadn’t seen. But they out-executed us and that’s what’s frustrating. We worked so hard to prepare for this game and really make sure we were on our responsibilities. And for them to have the type of game they had is frustrating.”

According to Kerrigan, the Redskins adjusted the alignment of their defensive front at halftime to attempt to close some of the running lanes the Eagles had been exploiting. Kerrigan said the Philadelphia offense presents problems both with its scheme and with the talent of its players.

“The scheme is designed to get guys in space and get guys in a lot of space with one-on-one matchups,” Kerrigan said. “So when you couple that with guys like LeSean McCoy and DeSean Jackson, Michael Vick — guys who are really good in space, that’s a strong suit for the offense. And they executed that well.”

What’s ahead:

● The Redskins practice at 1 p.m on Wednesday. Robert Griffin III, London Fletcher and Mike Shanahan speak with reporters afterward.

Have a Redskins question? E-mail Mike Jones at with the subject line “Mailbag question” for him to answer it in The Mailbag on Tuesday.

Follow: @MikeJonesWaPo |@MarkMaske | @Insider | Insider on Facebook

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The Takeaway (video): Jones on the loss | Post Sports Live’s takeaways

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