The Eastern Conference Final in the Audi 2021 MLS Cup Playoffs is officially set, with a slightly more predictable pairing than out West.

Don’t get me wrong, there's been chaos along the way. New York City FC’s win over Supporters’ Shield-winning New England Revolution on Tuesday night, for example, had enough wild energy to power greater Foxborough.

Even so, both Eastern Conference finalists had seasons that suggested they were MLS Cup contenders, particularly from an analytics and data perspective.

Unlike the finalists in the West, both the Philadelphia Union and NYCFC operated at a positive expected goals differential during the regular season. The Union finished sixth in MLS in xGD (meaning that they generated more xG than they allowed). The Cityzens finished first.

With an MLS Cup 2021 spot on the line, what should you have your eye on when these two Eastern Conference foes meet on Sunday at Subaru Park (3 pm ET | ABC, ESPN Deportes)?

Let’s dive in.

We saw it in Round One against the New York Red Bulls. We saw it again in the Conference Semifinals against Nashville SC. And you can bet your bottom dollar that we’re going to see it one more time on Sunday.

Jim Curtin’s team is going to try to destroy.

In both of their previous postseason matches, the Union sacrificed possession for large stretches of the game in order to prioritize their defensive shape and effectiveness. It’s an incredibly small sample size, but Philadelphia have allowed just 0.63 xG per 90 minutes in the playoffs according to Second Spectrum. Nashville and the Red Bulls aren’t elite attacking teams, but it’s clear the Union have kept their opponents from creating consistent, quality chances.

Zooming out a bit, Philadelphia have been a phenomenal defensive team throughout 2021. In the regular season, they allowed the third-lowest open-play xG per game while also averaging the fourth-highest pressing efficiency rating in MLS. The Union are more selective with their press than they were last year, averaging nearly eight fewer pressures in the final third per 90 minutes in the regular season and postseason in 2021 than they did in 2020.

Instead of pressing high all the time, Philadelphia use either a 4-3-2-1 shape or a 4-4-2 diamond shape and prioritize denying space in central areas. Of the eight teams that played in the Conference Semifinals, Philadelphia have allowed the fewest completed passes per 90 minutes in the central vertical strip of the field. Against Nashville, they funneled the ball wide and forced Gary Smith’s team to play from out to in, which you can see below. Many of Nashville’s key passes came from the wings and from the half-spaces, as opposed to the vertical center of the field.

NSH shots vs. PHI

The Union have been effective without the ball in the playoffs – and they’ve created a good amount of xG from open-play, which is somewhat surprising given their offensive struggles in the regular season. Of all 14 postseason teams, Philadelphia have created more open-play xG per 90 on possessions that don’t start with a dead ball than anyone else. And they’re the only team to have created more of that xG per 90 in the postseason than in the regular season.

In the postseason, the Union have put together a handful of sequences like this one, complete with a line-breaking pass from deep and a chipped ball into the box.

Despite their 1.4 total xG per 90 minutes in the postseason, the Union are only scoring 0.7 goals per 90 minutes. Over an extended period, Philadelphia’s scoring rate would likely improve and come closer to their xG. In the small window of the postseason, there’s no guarantee.

If the Philadelphia Union continue their stingy defensive ways and Sergio Santos remembers to bring his scoring boots on Sunday, they could be on their way to their first-ever MLS Cup.

The injury and suspension bug has taken a full-on, jaws-wide-open bite out of Ronny Deila’s team.

Anton Tinnerholm, Keaton Parks and Nicolas Acevedo have all been out with various ailments. Then Tayvon Gray pulled up with a late knock in Tuesday's game, though afterward he and Deila both said it was just cramps. James Sands could be another, too.

If all that wasn’t bad enough, Golden Boot presented by Audi winner Valentin Castellanos picked up two yellow cards on Tuesday against the Revs, leaving him suspended for the Eastern Conference Final.

Tinnerholm, Parks and Acevedo were already big misses. But losing Castellanos up top is a massive blow because of his work on both sides of the ball.

In 2021, the Argentine striker ranked first in the league in open-play xG. Few players in MLS are even close to as good at finding and exploiting space in the final third. Defensively, Castellanos ranked in the 99th percentile among forwards in distance closed while pressing and in the 98th percentile among forwards in pressures per game.

NYCFC won’t be the same without their No. 9.

But even without Castellanos, Deila's general tactical approach against the Union will feature many of the same principles as it has all season long.

In the regular season, New York City relied on using the ball to create chances: only four teams averaged more possession. Given the Union's tendencies, it seems logical NYCFC will have the majority of the ball on Sunday.

Without Parks and Acevedo, though, City’s possessions have become slightly shorter and more direct over the last month.

They’ll still control the ball (and the midfield) like they did against the Revolution in the Eastern Conference Semifinal, but they’ll also flip the script and give up a bit of possession to create counter-attacking opportunities, like they did against Atlanta United in Round One.

Regardless of how much possession they have, New York City like to play through Santiago Rodriguez and Maxi Moralez in the attack. With Moralez as the No. 10 and Rodriguez occupying the left, NYCFC have two players who thrive on combination play and can create chances for each other and their teammates.

Rodriguez’s ability to drive the ball forward (he’s in the 94th percentile among attacking midfielders and forwards in total defenders bypassed in the playoffs) paired with Moralez’s ability to pass through opposing players (he’s in the 97th percentile among AMs and FWs in defenders bypassed per 90 minutes in the playoffs), makes NYCFC extremely dangerous when they have the ball.

Philadelphia can expect Moralez to pull out little slipped balls like this one above that helped create Castellanos’ goal on Tuesday…

And for Rodriguez to slalom through the opposition as he did in this clip below against Atlanta.

Between the current gap separating the Union’s offensive chance creation and their chance conversation, questions around how NYCFC will operate without Castellanos and their injured players, and a chance to watch Rodriguez and Moralez try to break through a solid Philadelphia defense, there's no shortage of areas to pay attention to during Sunday’s Eastern Conference Final.