How did P.J. Fleck explain Gophers' terrible defense in loss to Northwestern?

In this story:
P.J. Fleck pointed to injuries and youth as reasons the Gophers shipped 38 points in Saturday's loss to Northwestern in Chicago.
The Gophers defense endured a torrid time at Wrigley Field, giving up 525 total yards to Northwestern including 305 through the air from QB Preston Stone. The 35 points scored by a Drake Lindsay-inspired offense was not enough for victory.
Fleck was put on the spot post-game about the defensive performance, and while he pointed to a series of injuries that necessitated the use of younger, less experienced players, he also said it's on him and his staff to get more out of the replacements.
A crucial injury loss for Saturday's game was cornerback John Nestor, dealing a significant blow to a secondary that is still reeling from the loss of Ethan Robinson and Justin Walley, both of whom left for the NFL last year.
Linebacker Devon Williams, backup safety Garrison Monroe, and backup corner Simon Seidl were also missing Saturday, while injuries have already ended the season of LBs Joey Gerlach and Drew Wilson and DT Mo Omonode.
" There's no excuses, but there are reasons," Fleck said on the defensive performance. "We've got a lot of guys out there that are playing for, a lot of them, the first time. They're really young players, this is the way you grow up.
"This is an investment program. And you know, behind a lot of our starters, a lot of depth, are young players. And they get an opportunity to play? They've got to go out there and be able to execute. We'll continue to challenge them.
"I'm responsible for putting people in the game. So transferring over the practice field to the football field, we've got to coach them better, and then we've got to be able to play better."
Fleck continued to say Northwestern took advantage of the Gophers' lack of downfield cover, as well as a lack of pass rush that gave Stone more time to throw.
"We didn't get to the quarterback very, very often, and we didn't cover well down the field. And when you put those two together, I mean, you're going to have all day to throw and they're going to complete them," he said.
"Got to get some guys back. Got to get some guys healthy. But our guys fight, fought, scratched, and clawed, and I'm proud of them for that," Fleck continued, adding: "In our type of program that we run, that we have, you can't skip steps. Does that mean playing a younger player? It means playing a really young player. And unfortunately, there was a bunch of young players out there. Now that means our older players have to lead them and play way better.
"We should, in that type of game, we've got to be able to overcome that. If that's going to be the issue, too many third and longs that were converted, too many second and longs that ended up being first downs. But that doesn't take away from how hard they play, and their resiliency and the resolve and their fight to keep going."
