In much of the soccer world, when managers write down their starting lineups, they start with their centerbacks.

That pairing or trio is the starting point for the formation as a whole, and the top unit is usually written in ink. Consistency matters as much as talent when defenders work together to cover opposing attackers.

You might expect Union manager Jim Curtin, a former centerback, to think that way. But this year he hasn’t. He has three starting-caliber centerbacks in Mark McKenzie, Jack Elliott, and Jakob Glesnes, and he hasn’t been afraid to rotate them. McKenzie and Elliott have been the most used pairing, to be sure, but Glesnes has played in eight of the team’s 13 games this year — including six starts.

Statistical analysis of centerbacks isn’t as straightforward as it is for other positions, but there are a few significant numbers to know. Glesnes ranks No. 2 in all of MLS in clearances per game (6.4), McKenzie ranks No. 5 (6.0), and Elliott ranks No. 13 (5.3). Glesnes also ranks No. 5 in accurate long ball passes per game (7.4).

And there’s the number that matters most: goals conceded. The Union are one of only six teams in MLS that have let in fewer than 10 in regular-season games. (Yes, they let in three in the MLS tournament knockout rounds, but not every team played in them.)

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“I’m a very lucky coach in MLS,” Curtin said. “Not many coaches, not just in MLS but all over the world, can say that they have three [centerbacks] that are able to play at the level that these guys are playing.”

He believes he’ll have to pick a top pairing “when the weather gets cold and the time comes for the final stretch" of the regular season, but right now “you’d be flipping a coin” to choose exactly which two would top the depth chart.

There are good reasons to hold off making the choice, beyond the impact of global warming. MLS has set its regular-season schedule only through the end of September, announcing Friday the slate for the rest of this month. The Union will have to play three games in a week again soon, and probably at least once in October.

So continued rotation of players will be necessary, not just helpful.

“There’s no reason to drive [players] into the ground right now,” Curtin said, a point emphasized by the Union’s unusually long injury list. Elliott, Kai Wagner, Sergio Santos, and Warren Creavalle are all questionable for the home game Saturday against New England (7:30 p.m., PHL17), and Aurélien Collin remains out while rehabbing a long-term leg injury.

The three new games on the schedule were announced Friday: Sept. 20 vs. Montreal at Red Bull Arena, Sept. 23 at FC Cincinnati, and Sept. 27 at home vs. Inter Miami, which just added a new star in striker Gonzalo Higuaín. The Argentine left Italian giant Juventus this week and arrived in Miami on Friday to begin a 10-day quarantine. (The Montreal game will be at Red Bull Arena so the Impact can stay in the U.S. for an extended time.)

All three games will be 7:30 p.m. kickoffs, televised on PHL17 and streamed online free on the Union’s website.

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MLS sets playoff format

In addition to announcing games through the end of September, MLS confirmed the format of this year’s playoffs. Because of the shortened regular season, 18 of the league’s 26 teams will qualify for the postseason.

The unbalancing of conferences for the year caused by Nashville’s temporary move to the Eastern Conference means the number of playoff qualifiers from each conference won’t be equal. Eight of the Western Conference’s 12 teams will make it, seeded 1 through 8, while 10 of the Eastern Conference’s 14 teams will make it. The East’s top six teams will get a bye and the 7 through 10 seeds will go to a play-in bracket.

That will lead to each conference having eight teams in the quarterfinal round. The worse seed of the play-in winners will face the No. 1 team, while the better seed will face the No. 2 team.

All rounds will be single-elimination, culminating in the championship game Dec. 12. As of now, the top team in the final will host the game, but it won’t be surprising if weather and the pandemic force the game to a neutral site.