Managers don't matter. Just ask the best manager in the world.

"I will tell you a secret," Pep Guardiola said in October. "The main thing is the quality of the players." He went on: "I try to figure out things, but at the end the players ... the success we had is because we have top players. This is the secret, no more than that."

Now, "managers don't matter" is a bit of a rhetorical overstatement. Manchester City wouldn't have won as many points last season if you were managing the team. Meanwhile, Chelsea probably wouldn't have finished higher in the table had they given you the reins rather than Frank Lampard after firing Graham Potter. Rather, what Guardiola is suggesting is that talent is the main driver of team success. Framed another way, player skill overwhelmingly decides what wins games. In fact, the authors of the book "The Numbers Game" found that player skill (as represented by wages paid) accounts for 70% of team performance. Somewhere in that remaining 30% sits the effect of the manager, along with other factors like, say, the random, and flummoxing bounce of the ball.

Managers do matter -- just way less than we think. And the limited impact makes that impact even harder to measure. In a league without a salary cap, and with massive team-to-team financial inequality and vastly differing team-building ideals, we can't just look at where a team finished and say, "The best manager finished first, the worst manager finished 20th."

Instead, we have to try to control for all of the other factors that influence winning. We can't do that with anything resembling precision because of all of the unknown factors that influence winning -- for example, is a player great because he's inherently great or because the manager deployed him in a way that made him great? -- so we're going to try a slightly different exercise.

And so, I've ranked and tiered all 20 Premier League managers by how confident I'd be that they would improve the 10th-richest team in the Premier League.

No-doubt improvers

Among the 20 managers in the Premier League, there are only two who I'm sure would improve the 10th-best team in the Premier League beyond their talent level. And those are the two best managers in the world: Pep Guardiola (Man City) and Jurgen Klopp (Liverpool). This exercise requires a ton of projection, and I really only have a small degree of confidence in all of the other tiers, but there's really no argument that anyone else belongs in this tier.

That said, such is the shape-shifting nature of managerial influence that there are some arguments against both of these coaches being in this tier.

With Pep, it's simply that we've never seen him do it. He's by far the most successful and most influential modern manager in the world. The ClubElo coach ratings also rank him as the best coach -- by a combination of how good his teams were and how much they improved after he arrived -- in the history of the sport. It's just that, well, he first had maybe the greatest player and the greatest midfield in the history of the sport at the same time, at Barcelona. At Bayern Munich, well, they have so much more money than everyone else, and they've won every league title since he left. And at Manchester City, he has the near-unlimited funding of a sovereign wealth fund.

I raised this idea to a former Premier League manager a few months ago, and he ... completely rejected it. Guardiola is easily the best coach we've ever seen at maximizing top-level talent, but as he suggested, so many other teams farther down the table have adopted some of his principles, too. If Brighton can play possession soccer and succeed with it, you can't really say that Pep Guardiola wouldn't do a great job at Brighton.

Klopp, meanwhile, has never coached the richest team in his own league. He's the last manager to beat Bayern Munich and Manchester City across a full domestic season. And he did a fantastic job at Mainz before Borussia Dortmund, too. Last season was probably his "worst" season as a manager -- he didn't really seem to figure out how Liverpool should play until the last couple of months -- but on the whole, he's just fantastic. One of the all-time greats. He's probably the best culture-builder in the sport, too.

These guys both now have decade-plus track records of success across multiple leagues, multiple countries and multiple tactical eras. No one else on this list comes close to that.

Failed at PSG -- but succeeded (almost) everywhere else

Mauricio Pochettino (Chelsea) and Unai Emery (Aston Villa) are sort of the anti-Guardiolas. Like every other manager in Paris since Qatar took over, they both flamed out at PSG. But the rest of their careers have mostly seen steady improvements at lesser-resourced clubs.

Pochettino was fine with Espanyol; then he seemed to transform Southampton into one of the most exciting teams in the Premier League, and then he seemed to transform Tottenham into one of the most exciting teams in the Premier League. We've already seen him succeed with two teams right around the realm of resources we'd be restricting him to in this exercise.

So why am I not more confident? Well, Ronald Koeman was quite successful for Southampton right after Poch, and this was during the club's golden age of recruiting. Then: How much credit should he get for coming in at Tottenham right when homegrown Harry Kane was blossoming into a superstar?

Emery, meanwhile, failed at Arsenal, but it's not like Mikel Arteta immediately did much better; they were awful the following season, too. Plus, taking over for Arsene Wenger was a near-impossible job, given that he was the last remaining capital-M manager, the kind who had a say in everything major that happened at the club. Outside of that, Emery has overseen improvements at Almeria, Valencia, Sevilla, Villarreal, and now Aston Villa. The latter featured an incredible in-season turnaround last year -- but how much credit should he get for it?

I'm pretty confident that neither Emery nor Pochettino would make our hypothetical team worse. I'm less confident in just how much they'll improve the performance.