The two biggest reasons the Eagles failed to make the playoffs this season were turnovers by the offense and big pass plays given up by the defense.

The Eagles had a league-worst 36 giveaways only a year after having 19. Twenty-one of those giveaways were interceptions by their quarterbacks — 11 by Mark Sanchez and 10 by Nick Foles.

Their defense had problems all year giving up big pass plays. The Eagles gave up a league-high 28 pass plays of 30 yards or more.

“I think ‘X’ plays defensively were a big factor in (not making the playoffs),” coach Chip Kelly said, referring to big pass plays. “If you look at two specific (reasons), it was turnovers on offense and X plays on defense.”

Last year, Foles had the third-lowest interception percentage in league history, throwing only two on 317 passes. But this year, he had 10 on 311 passes before breaking his collarbone in the Eagles’ eighth game of the season. He was replaced by Sanchez, who threw at least one interception in seven of nine games.

The big pass plays given up on defense were the result of a shaky secondary that likely will see three of its four starters replaced in the offseason.

“Like the interceptions, you’ve got to look at them individually,” Kelly said. “Did the quarterback have too much time? Or was it a blown coverage? Were we close in coverage, but didn’t make the play? There’s a lot involved.

“Last year, if there were two things we were really good at, we were good in the turnover category and we were good at not giving up X plays. We weren’t good at either of those this year.”

Cornerback and safety are expected to be two of the Eagles’ top priorities in free agency and the draft.

Cornerback Bradley Fletcher, who struggled badly in playoff-killing late-season losses to Dallas and Washington, will be a free agent and won’t be re-signed.

Safety Nate Allen is not expected to be back either. The Eagles’ other starting corner, Cary Williams, also probably won’t be back unless he agrees to restructure a contract that has an $8.2 million cap number in 2015.

Nolan Carroll, who was used primarily as the Eagles’ dime linebacker this season and started 22 games at corner for Miami in 2012-13, will be a starting candidate outside.

Rookie Jaylen Watkins, who can play safety and corner, also will get an opportunity somewhere, if not in the Eagles’ base defense then in nickel or dime.

But the Eagles also are expected to add at least one defensive back and probably more in free agency and/or the draft.

What they will do at the quarterback position isn’t quite so clear. A year ago, Foles was coming off an outstanding season and looked like he might be the long-term answer at quarterback.

However, he seemed to stumble under the weight of expectations this season before the injury.

Kelly would love to be reunited with his college quarterback at Oregon, Heisman Trophy winner Marcus Mariota. But that’s not going to happen. The Eagles have the 20th selection in the first round and Mariota is expected to be the first player taken in the draft.

Kelly probably will take a quarterback at some point, if not late in the first round, then possibly in the second or third round. But it would seem that Foles will be the Eagles’ starting quarterback again next September when he enters the final year of his rookie contract.

Foles is determined to prove to Kelly that he can be the team’s quarterback for a long time.

“They can draft whoever they want to, they can bring in anybody,” Foles said. “I’m going to compete. I’m going to be here. I’m not going to shy away from that.”

Foles acknowledged that he has to do a better job of protecting the football than he did this season.

“The interceptions, that’s something I can fix,” he said. “And that’s something I will (fix).”