How do you win the Champions League?

It turns out that "be Real Madrid" is not a bad place to start. The Spanish giants have won 13 European Cups, and no other club has more than seven. They've won four of the past six, and their current manager, Zinedine Zidane, has never not won the Champions League. Three tries and three trophies for Zizou, so that's that, huh?

Although Zidane The Manager has yet to be eliminated from the Champions League, other teams have in fact won the tournament.

As I wrote about in my newsletter, Liverpool grabbed it last year with a slightly throttled-down pressing approach that relied on their defense and their goalkeeper -- a sentence that would've been unthinkable just a year prior. Barcelona nabbed the trophy in 2015, thanks to the devastation wrought by Lionel Messi, Neymar and Luis Suarez. Bayern Munich did it the year before Pep Guardiola came to town by essentially fielding the entire World Cup-winning German national team, plus Arjen Robben and Franck Ribery. Chelsea took down Bayern the year before that despite finishing sixth in the Premier League, and the year before that was the most recent time Guardiola won it, with the Barcelona team that Sir Alex Ferguson said was the best side he'd ever seen.

Since the 2010-11 season, only five clubs have won the Champions League title. What did they have in common?

At first glance, there isn't a lot connecting any of those teams. But using domestic-play data from TruMedia, we can look at the statistical profiles of the past nine winners, see what the minimum benchmarks have been and compare them to all 16 remaining teams in this season's competition. We'll go through a number of categories and eliminate the 2020 teams that aren't up to snuff before landing on our One True Champion.

Let's get to it.

Measurement No. 1: Scoring enough goals

In domestic play, all of the previous nine winners averaged at least 1.7 goals per game. That low-point number, unsurprisingly, belongs to Chelsea. After all, they finished sixth in their own league that season; however, they sported a solid plus-19 goal differential and won the Champions League while Lionel Messi and Cristiano Ronaldo were at their peaks. We're not talking about a bunch of scrubs here. Plus, including an outsider team such as Chelsea in the numbers makes this exercise more interesting, as it accounts for the possibility of a non-favorite winning the whole thing.

We must say goodbye to Tottenham (1.6 goals), Napoli (1.57), Lyon (1.54), Valencia (1.43) and Atletico Madrid (1.00) at the first hurdle. No big surprises there, as none of those five sides is favored to advance to the quarterfinals, per FiveThirtyEight's Soccer Power Index. Goals, especially given that we're dealing with just more than half a season, can be statistically noisy; in other words, goals aren't necessarily predictive of more goals. But even if we look at expected goals -- a more predictive measure -- only Napoli (1.93) break the 1.7 threshold.

Teams eliminated: Tottenham, Napoli, Lyon, Valencia, Atletico Madrid
Teams remaining: Bayern Munich, Man City, Juventus, Real Madrid, Barcelona, Atalanta, Chelsea, Borussia Dortmund, Liverpool, RB Leipzig, PSG

Measurement No. 2: Goals against

Defense, it turns out, has tended to win championships over the past decade. Who knew?

Of the previous nine winners, five gave up fewer than one goal per match, and four of them -- both Barcelona sides, Liverpool and Bayern Munich -- were below 0.6. In fact, no team in this season's field is below 0.6 goals allowed per match, with Liverpool landing exactly on that mark. However, weaker defenses have won titles, too. Two of Zidane's Madrid teams, along with Carlo Ancelotti's Madrid team, allowed north of one goal per match. The worst defense, though, was, again, Roberto di Matteo's Chelsea, who let in 1.21 goals per game on their way to the trophy.

Despite that high figure theoretically creating a low barrier for entry into our exercise, four more teams are eliminated at this stage: Barcelona (1.22), Atalanta (1.35), Chelsea (1.36) and Borussia Dortmund (1.52). Dortmund are scoring at a higher rate than any team left in the tournament, a wild 2.82 goals per game, and Atalanta are third, with 2.65 goals per game. Plus, Atalanta are doing it in Serie A, where it has traditionally been difficult to score goals. Both teams should be neutral fan favorites, but their porous backlines mean their opponents are never out of a game.

Chelsea's defense doesn't seem likely to stand up against round of 16 opponent Bayern Munich (second among all teams with 2.76 goals scored per game), and as has been the trend the past few years in Catalonia, it's a shame Lionel Messi can't play defense, too.

Teams eliminated: Barcelona, Atalanta, Chelsea, Borussia Dortmund
Teams remaining: Bayern Munich, Man City, Juventus, Real Madrid, Liverpool, RB Leipzig, PSG

Measurement No. 3: Game control

Rather than looking at pure possession numbers, the next step after goals scored/allowed is to look at how the remaining teams control the field. How good are they at all the things that happen before the ball ends up in the net? To do this, we can see how many passes a team allows in their final third and compare that to how many passes a team completes in their opponent's final third. Then we can take those two numbers and determine a team's percentage share of final-third passes.

Unsurprisingly, Barcelona lead the way among the previous winners, but perhaps surprisingly, No. 1 is Luis Enrique's team, not Pep Guardiola's. The 2014-15 vintage completed 74% of the final-third passes in their matches, compared to the 10-11 side's measly 73.1%. Bayern, Liverpool and 2017-18 Madrid were also all north of 60%. Last place, once again, was Chelsea, with 56.1% of final-third passes.

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Of the remaining seven teams, none of them is below Chelsea's mark. City and Bayern are both above 70%, and Liverpool, Juventus, PSG and Real Madrid are all above 60%. RB Leipzig sit last, with 58.6%.

If looking at how teams tilt the field doesn't eliminate anyone, we can then look at how long a team keeps the ball when they get it. Opta records a statistic called "sequences" -- essentially, an interrupted chain of possession -- and no team that has won the Champions League since 2011 has had an average sequence time below 9.4 seconds. That low (again!) comes from Chelsea, but Ancelotti's Madrid weren't much higher, at 9.6. That means goodbye for Leipzig, whose average sequence time is 8.7 seconds, the second-lowest figure of all 16 knockout-round teams, above only Atletico Madrid's manic (7.3 seconds) approach.

Teams eliminated: RB Leipzig
Teams remaining: Bayern Munich, Man City, Juventus, Real Madrid, Liverpool, PSG

Measurement No. 4: Shots, shots, shots

The six teams left in this exercise are a bit harder to separate. If we look at how they press, all six are above the threshold of the previous winners. The minimum average starting point for all of their sequences -- a proxy for how high up the field they win the ball back -- is 47.7 meters from their own goal. That number belongs to Real, but they're still significantly above 2011-12 Chelsea's mark of 45.9 meters. Man City, for what it's worth, start their average sequence 53 meters from their own goal, which is higher than that of any of the past nine winners.

In terms of how fast they win the ball back -- something known as "passes allowed per defensive action" (PPDA) -- all six are lower than Chelsea's 13.26. Liverpool's high mark of 11.02 is still below where they were last season, when they, you know, won the Champions League. This season's most aggressive pressers are PSG (8.03), but they're still significantly behind Barcelona's mark of 6.98 in 2014-15. That side also scored more goals and gave up fewer goals than any other team in this season's field.

(Side note: Luis Enrique's team really might be the best of all time.)

Looking at how often the teams cross the ball doesn't do us any good either, so we're back to shots: How many do they take, and how many do they allow?

Like in PPDA, Liverpool are at the bottom, with 15.56 shots per game, but like in PPDA, that number is still better than that of last year's title-winning team. Because they're bottom in almost every number we've looked at so far, let us note that 2011-12 Chelsea took more shots (17.66) than all but three of the past nine CL winners.

How about shots against? Finally, some progress! Chelsea gave up 11.82 shots per game during the 2011-12 season, and this season, Juventus are giving up 12.3. That's actually the third-highest figure among all of the round of 16 participants, better than only that of Valencia and Tottenham. FiveThirtyEight's SPI gives Juve just a 3% chance to win the whole thing, and their inability to suppress shots is one of the biggest reasons they aren't in the top tier of contenders.

What about the quality of those shots?

All of the five teams left take above-average shots, in terms of their xG per shot. However, none of the previous nine winners allowed their opponents to take particularly good shots. The worst mark goes to Zidane's 2017-18 team (0.12), but that's right around the Europe-wide average. This season, though, there are two teams living by the mantra of "we don't normally give up shots, but when we do, we give up great ones."

Manchester City are conceding shots with an average of 0.15 per shot (worst among all remaining teams), and Bayern Munich are conceding chances with an average xG value of 0.13, which is third worst. Per FiveThirtyEight, Bayern (20%) and City (17%) are third-favorites for the title behind Liverpool (21%). The low-quantity-high-quality defensive approach works in domestic leagues in which both clubs have a significant talent advantage over almost all of their opponents, but it could implode once the competition heats up.

Teams eliminated: Bayern Munich, Man City, Juventus
Teams remaining: Real Madrid, Liverpool, PSG

Measurement No. 5: Fouls

Listen, we're nitpicking here, all right? One of the only remaining differentiating factors for these three teams is how often they foul their opponents. Among the past nine champs, only one committed more than 12 fouls per match: 2012-13 Bayern Munich, who hacked down the opposition 13 times per match. At the other end sit last season's Liverpool, who committed 8.29 fouls per game.

While the highlight of the Real Madrid season so far is Federico Valverde's game-saving, last-minute, last-man, red-card tackle on Alvaro Morata in the final of the Spanish Supercopa, the team's wider penchant for foul play earns them the boot from our list. Zidane's team commits 13.22 fouls per match.

For whatever reason, none of the recent winners other than Bayern has fouled anywhere near that much. It could speak to a larger lack of control that then shows up in other areas of the game. It could lead to too many set pieces, which lead to the kind of scripted moments that often decide knockout games. Or, as Madrid fans will surely be hoping, it could be totally random.

Teams eliminated: Real Madrid
Teams remaining: Liverpool, PSG

Measurement No. 6: Passes

And then there were two: Liverpool and PSG, who played a pair of the more thrilling group-stage matches in last season's tournament.

It sure seems as if PSG are trying to find a new absurd way to exit the competition every year. First, it was La Remontada, when they blew a 4-0 first-leg lead to Barcelona. Then they bought Neymar, the Barcelona player who led that comeback, only for him to miss the second leg of their round of 16 matchup with eventual winners Real Madrid. Then last year, of course, Neymar didn't play in either match against Manchester United, and despite winning the first leg at Old Trafford 2-0, PSG were eliminated by a last-minute penalty awarded by VAR for a handball on a shot that probably wasn't going to end up anywhere near the goal frame.

However, this season's PSG have more in common with the previous nine Champions League winners than anyone else, including last year's champ. None of those teams completed fewer than 84.5% of their passes, with both Liverpool and Chelsea tied at the bottom of the threshold. This season, Liverpool have dropped down slightly, to 83.7%, a barely perceptible shift that, for the purposes of this exercise, eliminates them from the list.

PSG, meanwhile, are completing 89.9% of their passes, which is a higher percentage than that of any other team left in the competition. Sure, they play in the worst league among the Big Five, and yes, they have an incredible resource and talent advantage compared to their domestic opponents. But is it really a surprise that a team with Neymar and Kylian Mbappe -- arguably the two best non-Messi players in the world right now, the kind of talent who can decide a tie all on their own -- has the profile of a Champions League champion?

As long as they're both out there, PSG can beat anyone. Of course, they've played together in only one Champions League knockout match since they joined the team in the summer of 2017.

PSG kick off the round of 16 against Dortmund next week, and like clockwork, Neymar hurt his ribs and hasn't played a league game in more than two weeks. (Mbappe is also skipping this weekend's game vs. Amiens.)

We'll give them one more shot, but depending on how things go over the next few months, next season's version of this exercise might include another filter, one that says "Not PSG."