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It's a strange and wonderfully weird time to be a Philadelphia Eagles fan. A city filled with canine masks and Crisco-greased poles has fully embraced its underdog status.

As the city recovers—this includes nursing wounds left by poles that weren't lathered up—there will surely be another spike in sales of creepy dog masks. The Eagles' underdog label isn't going anywhere, as the New England Patriots are early five-point favorites in Super Bowl LII.

Nothing has changed for a team widely discarded after quarterback Carson Wentz, an MVP front-runner, suffered a season-ending ACL tear in Week 14. Nothing should change going forward either, including the Eagles' winning formula of a punishing defense and a mismatch-creating tight end.

That's the key: They need to make Zach Ertz the centerpiece of their Super Bowl blueprint by highlighting the clear comfort quarterback Nick Foles has when throwing to him.

Being at ease and in rhythm is like a heartbeat for any quarterback, and especially for a backup thrust into a high-intensity situation. Foles was pushed into a starting role for a surging team and relied heavily on Ertz as his cozy source of security while leading the Eagles to home-field advantage in the NFC.

Including the playoffs, Philadelphia has played five games with Foles at starting quarterback. The Eagles' only loss during that time came during a meaningless Week 17 game against the Dallas Cowboys when starters, including Foles, sat for much of the afternoon.

Ertz has been a stud all season and was selected to the Pro Bowl for the first time after finishing the year third among tight ends with 824 receiving yards on 74 receptions. He was a target magnet, but the gravitational force of his presence has grown stronger since Foles entered the huddle.

Ertz has been on the other end for 27.7 percent of Foles' passing yards and 29.2 percent of his completions in his five starts. Meanwhile, Alshon Jeffery, the Eagles' second-most productive pass-catcher during the regular season, has connected with Foles for 19.7 percent of the quarterback's passing yards and only 14.6 percent of his completions.

Ertz had 93 yards on eight catches against a usually intimidating Minnesota Vikings defense in the NFC Championship Game. It was a night of dominance highlighted by a 36-yard chunk play when Ertz completely fooled safety Harrison Smith.

Smith was the top-rated safety by Pro Football Focus in 2017. He's not often seen chasing and flailing, but Ertz has that effect on even the most fundamentally sound defenders.

A tight end doing anything of note against the Vikings was stunning, and it became clear pretty early that something special was happening. At the 11:11 mark of the second quarter, Ertz caught a 15-yard pass, and as Reuben Frank of NBC Sports Philadelphia noted, that was already the third-most yards allowed to a tight end by the Vikings in 2017.

His night of destruction came against a Vikings defense that ranked second against tight ends, allowing 37.8 yards per game to the position, according to Football Outsiders. Much of Ertz's yardage came in clutch third-down situations too, which is simultaneously the most impressive and essential quality of the Foles-to-Ertz connection.

Ertz finished with four catches for 44 yards on third down. One of his conversions came on a 3rd-and-10 to extend an early drive that ended in a touchdown and put the Eagles up 14-7. It was a lead they never relinquished.

Fran Duffy of the Eagles' official site broke down how the Eagles use Ertz creatively on third down, and why he's become such a reliable target with his fluid route running and ability to separate:

The Vikings had one of the best third-down defenses in NFL history. They finished the regular season having allowed only 51 conversions on 202 attempts. That resulted in the best conversion percentage since the league started tracking the statistic in 1991 (25.2 percent).

Yet there was Ertz, torching that historically great third-down defense while Foles looked to him repeatedly. As a result, the Eagles converted on 10 of their 14 third downs.

For their next act, Foles and Ertz will have to duplicate that success against a Patriots defense also known for surrounding and swarming opposing tight ends.

The Patriots defense ranked eighth against tight ends during the regular season, according Football Outsiders, giving up an average of 44.9 receiving yards per game, which was 5.7 yards better than the league average.

The Patriots faced two of the four tight ends who finished 2017 with 800-plus receiving yards (a list that includes Ertz). They didn't shut them down, but the safety duo of Duron Harmon and Devin McCourty wasn't exactly scorched either. The Patriots limited the Chiefs' Travis Kelce and the Titans' Delanie Walker to a combined 89 yards on eight receptions (11.1 yards per catch) when they played those squads.

But Ertz has fared just fine against defenses that play tight ends tough. That goes beyond the Vikings, as he scored two touchdowns against the Carolina Panthers (fourth vs. TEs) and one on the San Francisco 49ers (fifth). He also recorded six receptions for 61 yards and a touchdown against the Arizona Cardinals back in Week 5 (seventh).

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The Patriots had the league's 30th-ranked pass defense after allowing 251.2 yards per game in the regular season. They're fresh off giving up 293 passing yards and 8.1 yards per attempt to Jacksonville Jaguars quarterback Blake Bortles.

Ertz has a way of exploiting the vulnerabilities of even the best secondaries. We saw that against the Vikings, when his threatening combination of size (6'5", 250 lbs), speed after the catch and physicality to win jump balls led to a win in a difficult matchup.

He has used those tools to produce seven 80-plus-yard receiving games so far this year, including the playoffs. But more importantly, Ertz has proven to be just as reliable with an MVP-caliber quarterback as he is with one set to make only his sixth start of the year in Super Bowl LII.

Foles trusts him in traffic, in the red zone and on third down. Most of all, he should trust Ertz to be the primary difference-maker as the underdog Eagles keep clawing and looking for the franchise's first shiny set of Super Bowl rings.