Eagles coach Doug Pederson, asked why Carson Wentz seems to be regressing in his fifth season, acknowledged Monday that it was “a good question.” Pederson said he thinks Wentz will be better the more he works with his receivers, some of whom are new and some of whom — such as Miles Sanders — missed a lot of preseason work with injuries.

But Pederson also branded as “unacceptable” the third-quarter interception Wentz threw in Sunday’s loss, with the Eagles at the Rams' 21, first and 10, down by just 21-16 in what became a 37-19 defeat.

“That one is not part of the play,” Pederson said. “It’s a backside progression, obviously, and it’s unfortunate.”

Pederson didn’t really explain what he meant by “not part of the play.” He said he must do a better job of “coaching the details of that particular route. It was a little bit of a new concept for us in the game plan this week.”

He added that Wentz would agree on the “unacceptable” characterization. “We’ve got to own that one,” he said.

Pederson also was asked about the status of left guard Isaac Seumalo, whose left knee was rolled up on during an Eagles touchdown run Sunday, 25 offensive snaps into the game. Matt Pryor played the final 46 snaps.

Pederson said Seumalo will “miss some time” and go on “the short-term IR.” This year, players can return from injured reserve in as little as three weeks. The Eagles will have an extra roster spot when Seumalo gets that designation.