FOXBORO, Mass. — Jerod Mayo’s walk back to the locker room was slow. It was an eerie evening here. Foggy, dark, foreboding. Even though his tenure has lasted only 16 games, Mayo’s done this walk several times, the sulked retreat to the locker room after a performance that feels like rock bottom only for a new low to arrive.

But this one feels different. This one really has to be rock bottom. The kind that leads to change.

For weeks, the New England Patriots have signaled to every NFL insider with a cell phone that they really wanted Mayo to return for a second season as head coach. Robert Kraft had made Mayo the handpicked successor to all Bill Belichick built. They knew he’d have learning moments as a first-time head coach. But they really wanted it to work out. Essentially, the message was this: Just don’t make the Patriots an embarrassment, and you’re back for Year 2.

This one, though — Los Angeles Chargers 40, Patriots 7 — leaves no doubt. The Patriots are an embarrassment. They’re 3-13. They haven’t scored 30 or more points in 44 straight games. They’ve surrendered at least that many six times this season alone. They hadn’t lost six in a row since 1993 — now they’ve done it twice this year. For a second straight season, they’re going to finish with a sub-.300 winning percentage, something they haven’t done since they were the AFL’s Boston Patriots.

All of which is to say more simply: It’s time.

Time for change. Time for Kraft to admit this has all been too much too soon for Mayo and set sights on hiring Mike Vrabel to be the Patriots’ new head coach.

Kraft’s plan seemed a reasonable one once upon a time. Mayo seemed a natural successor to Belichick. He played for him and was lured into coaching by him. He could take Belichick’s core beliefs and pair them with a more modern approach. It seemed like it had a chance to work. And what a story it would’ve been.

But 16 games in, it’s painfully obvious that Mayo is in over his head. Perhaps it wouldn’t be this simple if the crop of available coaches was a group without any ties to the Patriots who may not even consider a franchise that’s been in the wilderness since Tom Brady left five years ago.

What should make it an easy decision for Kraft is that the fix is obvious. One of the two best available coaches is a Patriots Hall of Famer, a tough, no-nonsense guy who could both be a bridge to the glory years while yielding optimism about what’s to come in Foxboro. In short, what Mayo was supposed to be.

Another way to look at it is this: The best case is that Mayo turns things around, gets buy-in from players, and with more talent on his roster, yields the kind of culture Vrabel built in Tennessee while getting the most out of his teams. But if that’s the hope, why not just hire Vrabel?

Mike Vrabel is the obvious choice for the Patriots if they move on from Jerod Mayo after one season. (Eric Canha / USA Today)

There’s no guarantee most years that other free-agent coaches would have any interest in the Patriots. But Vrabel would. He could return to the franchise where he became a three-time Super Bowl champion as a driving force of the first dynasty. And, importantly, he has a good relationship with Kraft. The Pats owner wined and dined Vrabel during the Titans’ bye week last year when Vrabel was inducted, rolling out the red carpet as a thank you for all Vrabel meant to the Pats (and maybe as an apology for trading him in 2009), which at the time irked some back in Tennessee watching Vrabel bask in all things Patriots. Even if the Patriots job wouldn’t be all that intriguing to some coaches, that’s not the case with Vrabel.

At this point, what’s the argument for bringing back Mayo? Just that Kraft once saw a lot of promise in him and they owe it to him to give him a chance with a better roster? Is that enough to let Vrabel go elsewhere, then potentially have to make a switch next year if things don’t work out and have to search through a new crop of available coaches who don’t have ties to the Patriots?

That path would mean changes to Mayo’s coaching staff, potentially swapping out his offensive and defensive coordinators. Alex Van Pelt’s offense has been really bad, and somehow DeMarcus Covington’s defense has been even worse. On national TV Saturday, the Chargers had 428 yards to the Patriots’ 181. They had 29 first downs to the Patriots’ 11. They had the ball for more than two-thirds of the game.

Back at the bye that started this month, the mandate to Mayo and his coaching staff seemed obvious. Just don’t become a trainwreck at the end of the season. Show some improvement here and there even if it doesn’t add up to a bunch of wins.

But in the three games since then, the Patriots have been blown out by the Arizona Cardinals, blew a 14-point lead to the Buffalo Bills and got blown out by the Chargers.

Everything about the latest one was embarrassing. Ladd McConkey, the rookie receiver they didn’t want in the second round, torched them for two touchdowns and 94 yards — outproducing the combined season-long effort from the receivers the Patriots drafted instead (Ja’Lynn Polk and Javon Baker). The defense was gashed and lost its best player (Christian Gonzalez) to injury. The offense stunk and got Drake Maye smoked a few times.

Even the odd parts of this team that don’t really matter are embarrassing, like Mayo telling the broadcast crew before the game that they were going to start Antonio Gibson at running back to send a message to Rhamondre Stevenson … only to then start Stevenson.

“Coach’s decision” was all Mayo could muster three different times when pressed on the move.

At this point, he’s a coach without answers. Maybe if he had another year to be a mentee under Belichick this could’ve worked out. Or maybe if Eliot Wolf’s draft class hadn’t been a total disaster outside of Maye then Mayo could yield more production with a better roster.

Instead, Gillette Stadium was dotted by empty seats Saturday, an uncomfortable reminder of where they’re at.

Kraft invited Maye’s family to watch the game from his suite high above the 50-yard line. It’s obvious the Patriots feel they have their franchise quarterback. They owe it to him to surround him with better players — and, based on the last 16 games, better coaches.

The hope was that Mayo would get better as the season went on and he learned the ropes of a new job. His team would reflect that improvement.

Instead, the Patriots found a new rock bottom on an afternoon when an uncomfortable reality set in. It’s time to make another change at head coach.

(Top photo: Kathryn Riley / Getty Images)