Rock Observation Sheet

(Editor's Note: With news on May 20 that Liverpool have confirmed Arne Slot as manager, we're republishing this piece from May 1 that breaks down what made him the right person to succeed Jurgen Klopp.)

It seems like Liverpool might finally have their man.

Per ESPN sources, the club has agreed to a fee with Feyenoord to buy out the final two years of manager Arne Slot's contract. Provided that Liverpool and Slot can come to a deal, the 45-year-old Dutchman will be the one tasked with the simple challenge of, you know, replacing the manager who has won every major trophy he could win and reestablished Liverpool as one of the top clubs in the world.

No pressure, Arne.

Rather than going for a big-name manager to replace perhaps the biggest-name manager in Jurgen Klopp, Liverpool landed on someone whom many of their fans have never heard of. When Klopp joined the club 8½ years ago, he was already one of the world's few elite coaches. He'd won the Bundesliga multiple times and reached the Champions League final. Slot, meanwhile, has never managed outside of the Netherlands and has coached six Champions League matches -- total.

So, in anticipation of Slot, uh, slotting in at Anfield, we have some questions. Starting with...

The first thing to remember here is that this is Liverpool. Former director of football Michael Edwards, who helped build the all-conquering squad of the past decade, is back, and the club's current director of research, Will Spearman, has a doctorate in physics from Harvard and helped discover the "God particle" before he was brought in to help figure out who might be a decent soccer coach.

The point is: Liverpool's managerial hiring process will be more rigorous, data-driven, targeted and objective than that of any other big club in the world. They know what they want from their coach and, unlike most other clubs, they've tried to figure out how to measure what they want from their coach.

This is why they've landed on a coach who no one really expected to become the next Liverpool coach back when Klopp announced he'd be leaving in January.

Based on who they are hiring, it's quite clear that Liverpool wanted a coach to provide a continuation of Klopp's current approach.

The prevailing tactical style at the highest level of the sport right now is defined by one word: control. The likes of Manchester City's Pep Guardiola and Arsenal's Mikel Arteta have their teams playing in ways that attempt to eliminate risk, on both ends of the field. They play more traditional defenders than we would've seen five or 10 years ago, and then those traditional defenders don't get forward as much as full-backs would've in the past. Their matches feature increasingly few possessions because their players play quite conservatively when they're on the ball.

Not Klopp, though. He and Liverpool have decided that the best way to win games over the long run is to take risks -- to be OK with possession turning over, to be OK with the other team running into space, at pace. The thinking is: "Well, we have better players than you, and the way for that to show itself over 90 minutes is for us to create the kind of chaos where our attackers have plenty of opportunities to attack into space." The opponent will also get plenty of these opportunities, but Liverpool are confident that their own defenders will be better than the opponent's attackers.

Here's a chart, comparing each Premier League team's pass-completion allowed with the number of possessions it averages per game:

Liverpool press more aggressively and effectively than anyone else in the league -- duh -- but you'll see that the other most effective pressers are Manchester City, Arsenal, Spurs and Chelsea. Or, most of the other big clubs in the country. However, the only two teams whose matches feature more possessions than Liverpool are Bournemouth and Everton. Ranked right behind Liverpool are Luton Town, Crystal Palace and Brentford.

In other words, Liverpool are aggressive without the ball (low pass-completion numbers allowed) and with the ball (high number of possessions per game).

And guess who else plays like this? Arne Slot's Feyenoord.

Liverpool's games feature 94 possessions per match, while Feyenoord are at 96. Liverpool's opponents complete 77% of their passes, while Feyenoord's complete 74%. Liverpool's average pass travels 17.1 meters, while Feyenoord's goes 17.2 meters. Liverpool move the ball upfield at an above-average rate of 1.26 meters per second, while Feyenoord go even faster at 1.33 meters per second.

Here's how Feyenoord match up with the rest of the Eredivisie in expected goal differential per game since Slot took over in the summer of 2021:

If expected goals, or xG, isn't your thing -- thank you for hate-reading this column -- Feyenoord are also second in the Eredivisie in both points and goal difference since Slot took over.

The quality of a team is not a one-to-one correlation to the quality of the manager. In fact, it's not even close to that.

The manager's job, in the simplest sense, is to make his collection of players perform at a higher level than the average coach would get those same players to perform at. Coaches can coach only what's in front of them: the squad, which is essentially a representation of the team's resources.

While Eredivisie wage data is a bit tougher to come by, the football finance analyst Kieran O'Connor broke down Feyenoord's financial records a year ago, during the club's title-winning season. As he wrote in his newsletter, The Swiss Ramble: "Feyenoord's €48.2m wages were ... less than half Ajax's record €109.4m and also lower than PSV €55.2m. On the other hand, this was nearly twice as much as fourth placed AZ €25.3m."

This season, Feyenoord's non-penalty xG differential is the third highest in Stats Perform's entire Eredivisie dataset, which extends back to the 2012-13 season. It's bettered only by Ajax in 2019-20 and PSV this season.

So, Feyenoord are one of the richest teams in the Netherlands, but not the richest. Slot has them playing at a higher level than almost any other team over the past 15 years -- and yet they're not going to win the league because one of their richer rivals has been even better.

Yeah, he's going to fit right in at Liverpool.

Remember that 2019-20 Ajax team I just mentioned? That season, Slot managed AZ Alkmaar -- the fourth-richest team in the Netherlands. The season was canceled due to COVID after 25 games, but Slot's team was tied with Ajax atop the table, on 56 points.

Per the wage info from The Swiss Ramble, Ajax's spending power is roughly four times AZ's. And although they weren't quite as good as Ajax that season, their plus-1.02 xG differential ranks in the top 25 of all Eredivisie seasons since 2012. It's one of only two seasons to come from a team not named Ajax, PSV or Feyenoord.

At both AZ and Feyenoord, Slot's teams have performed at close to the maximum level of what you could expect from a club of their size. Combine that with the style of play, and that's why Arne Slot is going to be the next Liverpool manager.

Yes, the nerds plugged a handful of variables into their spreadsheets, clicked enter and a flashing image of Slot's smiling, bald head appeared on their computer screen. (In case it's not obvious: that was sarcasm.)

Obviously, you use the numbers to help you winnow down the possible candidates for the position, but then you have to consider their personalities, their leadership styles, their tactical flexibility, their attitude toward young players, their temperament and plenty of other so-called soft factors. You also can't really know any of these things until you actually hire the person, either. It's why hiring is so hard -- no matter the field.

However, Liverpool also certainly want a manager who can fit inside of their decision-making structure, rather than outside of it. Per reporting from the Times of London, Slot's role will be as a head coach rather than the traditional manager. Edwards has returned to Liverpool in a new, higher position, as CEO. Below him, they've brought in Richard Hughes from Bournemouth to the new director of football. I hate how the "slot" jokes keep writing themselves, but yes, Slot will slot into that structure, a structure that's quite common in the Netherlands, where the coach coaches the team and has a partial say in player recruitment.

Liverpool's success was built on a brilliant recruiting strategy combined with a brilliant coach who was open to the players being suggested to him. That seemed to change after Edwards left the club, as Liverpool went from signing undervalued players who were already effective to players like Darwin Núñez and Cody Gakpo -- the former a raw and expensive forward who had just torched Liverpool in the Champions League, and the latter one of the standout players from the inflation-inducing 2022 World Cup. These are the kinds of players coaches want -- ones they saw playing well and then imagine playing well for them -- but not the kinds of players who'd be targeted by people who have a broader understanding of the transfer market and its dynamics.

Sources in the Netherlands have told me that Slot is more interested in data than most managers, something that likely attracted Liverpool to their new coach. It also wouldn't surprise me if there was some kind of discussion around player health. It's impossible to look at Liverpool's past two seasons, both filled with massive injury crises, and not connect it to the demanding physicality of Klopp's approach. For all of Klopp's virtues, there's no way the club wants that to continue.

In the 2014-15 season, Klopp's Dortmund suffered through one of the unluckiest seasons of the past 10 years. In the Bundesliga, they finished with a plus-5 goal differential -- despite posting a plus-23.4 xG differential. Thanks to a freakish season of poor finishing luck on both ends of the pitch, the second-best team in Germany finished in seventh.

Klopp seemed burned out by the years of trying to keep pace with Bayern Munich and a season where it seemed like every bounce went against him. Dortmund, too, seemed happy to move on after the seventh-place finish. From the outside, it looked like Klopp's methods had worn the club out, but really: the shots just didn't go in.

So, in the fall of 2015, with the team stuttering for the second straight season under Brendan Rodgers, Liverpool were able to hire one of the best managers in the world. Klopp had consistently outperformed his budget at Dortmund and helped popularize the high-pressing style that was sweeping European football. With the deep connection he'd cultivated with the fans at Dortmund, he seemed like the perfect coach for Liverpool. Turns out, he was.

In 2024, there is no obvious perfect coach for Liverpool. Klopp is leaving, Pep Guardiola isn't crossing the rivalry to swap Manchester City for Liverpool, and Carlo Ancelotti is winning trophies with Real Madrid. Beyond those three, there really are no other coaches who have shown the capacity to consistently win at the highest level over a long period of time.

Mikel Arteta seems great, but we've never seen him coach anywhere other than Arsenal, and his success directly coincides with his club getting way smarter about recruitment and filling the roster with young talent. Xabi Alonso is currently experiencing a magical season at Bayer Leverkusen, but we've still seen him coach professional soccer only for less than two seasons. Julian Nagelsmann quickly wore out his welcome at Bayern, and so too did Thomas Tuchel. Roberto De Zerbi has been great with Brighton, but he also has been powered by perhaps the savviest front office in the sport.

If you're hiring a manager in 2024, you're taking a big risk. That's what Slot is because it's what anyone would be.

The numbers all check out. He's got plenty of charisma. He seems inquisitive and open to new ideas. He has improved two separate clubs and had them both humming at a level way beyond what their wage bill should allow.

But still, the leap from Feyenoord to Liverpool is a massive one -- as is the jump from the Eredivisie to the Premier League. The defenses that Slot's team will have to break down in England are going to be way more organized and way more talented than what he has typically faced in the Netherlands.

There simply haven't been many Dutch managers who've successfully made the leap from the Eredivisie to one of Europe's "Big Five" top leagues. Erik ten Hag is the latest example of a manager failing to figure it out, but the same goes for the likes of Ronald Koeman, Peter Bosz and Mark van Bommel. This doesn't mean that Slot can't succeed, but it should at least temper your expectations by a percentage point or two.

The biggest issue, though, isn't a tactical or an analytical or a translatability issue. The biggest issue is that there's no one else like Klopp.

Klopp is one of the most charismatic people in the world, let alone the sports world, let alone the soccer world. He's a living legend of the sport, and it makes a huge difference when you're recruiting a player to Liverpool -- on average, a less appealing location than London or Paris or Madrid -- and you can sit him down with Klopp. Hearing Jurgen Klopp tell you he wants to coach you is going to mean more than hearing it from Arne Slot or anyone else that the club could've hired to be the new manager.

That won't necessarily be true forever, and despite the club's poor results over the past few weeks, Liverpool are still in great shape for the future with a new front office intact, the team playing at a very high level, and lots of young talent throughout the squad.

Still, whether it's Slot or someone else, Liverpool's next great manager is going to have to become a great manager while he's at Liverpool. Their current great manager, who is stepping down at the end of the season, was already a great manager before they hired him.