SOUTH BEND, Ind. — If you wished to commit sunniness over the 52-20 woe that befell Navy on a mean, cold Saturday at Notre Dame Stadium, you might say the No. 23 Midshipmen have answered their 3-10 nadir of 2018 with a season in which what befell them could register as a shock.

The esteemed coach Ken Niumatololo, in his 12th season, went to halftime with one of the hardest, quirkiest coaching tasks: talking to a team trailing 38-3. (“Yeah, a lot of psychological stuff,” he said, soon adding, “We were all in shell shock.”) The margin grew to 45-3 before settling.

No. 16 Notre Dame romped around the field with precision and merriment. Chase Claypool, its wide receiver from the unexpected yet enviable home area of British Columbia, made four touchdown catches of high skill and variety on passes from quarterback Ian Book, himself a case of high skill and variety.

The Midshipmen (7-2) spilled fumbles, four of them. The Irish (8-2) collected fumble recoveries: one for Asmar Bilal, one for Jaron Jones, one for Drew White and a closing Notre Dame score for linebacker Paul Moala, as reward for invading the backfield early in the fourth quarter and flicking a pitch eventually to himself for a 27-yard touchdown return. Malcolm Perry, the admirable Navy quarterback, fumbled thrice, even if two came through defensive quickness, with one through a messy fake handoff.

All told, it grew necessary during the game to remind yourself that it featured two ranked teams, with Navy entering at No. 23 in the College Football Playoff ­selection committee’s estimation. A promising game full of ranked teams ended with Notre Dame Coach Brian Kelly saying, “Fun day,” and with Navy having spent this good season earning a right to be disappointed.

Unlike last year, when Notre Dame roared to a 27-0 lead against a downtrodden Navy, the Midshipmen brought momentum this time and still wound up with a halftime during which, Niumatololo said, “Heads are hanging.” His team had just squeezed out a field goal at the first-half horn to draw within 38-3. A faint cheer had wafted from the Navy band on the other side of the stadium, which with 74,080 witnesses saw the first non-sellout here since Thanksgiving Day 1973.

It became one of those days that makes a strong person say, “It’s beautiful about this sport, and the beautiful thing about life is, always new opportunities, right?” That’s how center Ford Higgins put it as Navy rolls on back into American Athletic Conference play and senior day next week against SMU.

“Yeah, we’ve been playing so well and got a lot of good things going on this year,” Niumatololo said. “We just — coming into this game we had a lot of momentum, and we definitely didn’t see that coming. So it was a shell shock to me, to all of us. And you know, that starts with me, and they obviously hit us in the lips, and we couldn’t respond.”

It sent him rummaging for old boxing terminology. “They, like, hit us with the overhand right, and we were dazed the rest of the game, you know,” Niumatololo said. “And we didn’t respond very well. You know, we haven’t been in that situation this year, and we were dazed the whole game, and to their credit, a lot of it was them.”

The overhand right began straightaway. Notre Dame went 75 yards in 11 plays. Book started his path to 14 for 20 and five touchdown passes — all in duty limited to the first half and just one series of the second — by throwing the ball around accurately: to Claypool on the right, to Chris Finke in the middle, to Claypool through the middle for a simple seven-yard touchdown. Book even improvised for the crucial play of the trip, his 15-yard scramble up the right sideline on third and 16, which set up a fourth and one, which the Irish converted easily with Tony Jones Jr. bulling forward.

The Irish led 7-0, but all right, then Navy got the ball, kept it for 11 plays and traveled to the Notre Dame 24-yard line. It’s just that on the 11th play, the leaks began to spring. Perry took the snap and turned to his left, and as he prepared to pitch to CJ Williams, Notre Dame defensive lineman Khalid Kareem appeared right behind Perry with unhelpful intent.

Kareem hugged Perry and plucked the ball out. On the next Navy possession, with the score by then 14-0, Kareem reached through a blocker to pluck the ball away from Perry again. Three more Navy possessions, the score by then 31-0, and Perry lost the ball while withdrawing it from his fullback. By then, it seemed fumbles were rolling around the floor all over the place as they would in a wee-hour nightmare.

“We had to play almost perfect to beat these guys,” Perry said, “and fumbling doesn’t help you beat anybody. I take ownership of that. And, yeah, the fumbles hurt. . . . Turning the ball over is not something that we do here at Navy. We can’t afford that.” They had come in with a turnover margin of plus-one, a pretty good 57th in the country, and left at minus-three.

Meanwhile, Notre Dame receivers roamed the prairies. On the play that made things 14-0, a 47-yard pass from Book to Claypool, who caught seven passes for 117 yards, Claypool said, “We knew it was a mismatch or a miscommunication of some sort” from right around the snap. And so: “I was running down the field with a smile on my face before the ball was even thrown.”

It felt like snowballing, even if athletes described it in the way they must, to maintain confidence. “I wouldn’t say things were snowballing,” Navy linebacker Nizaire Cromartie said. “I just thought they were getting good plays, and a mix-up here, an absence of coverage over here, absence of getting to the ball when you rush the Q, that’s definitely going to hurt.” Said linebacker Paul Carothers: “I was not sitting there thinking about how this got away from us. It was like, What are they going to do on this play? What’s my position doing, if I was out there or I wasn’t out there?”

They did that to the end, when the teams joined in one stadium corner and then the other for the two school songs, then the Midshipmen moved along to the rest of the season because life always brings new opportunities. They will try to expunge from mind a day of which Niumatololo said, “They kicked us in the teeth, kicked us in the gut,” and, for Navy, those things again felt strange.

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