Creating a successful team for the long-term in any of Europe's big five leagues is about far more than simply bringing together 11 talented individuals on a matchday.
When we think of the great teams throughout history, each of them has had their own unique identity, moulded through time spent as a unit.
In the modern game, the frenetic nature of the transfer market means that it is increasingly challenging for clubs to effectively build up relationships and understanding between players which can prove so vital in big moments.
The average age of a squad and a club's stance when it comes to handing out long-term contracts can also play a part in determining whether a given team is well-equipped for the future.
Now, using a system known as the Sustainable Squad Management (SSM) index, has ranked the most sustainable squads across Europe's major leagues.
Age structure, group stability and contractual policy have all been used to compile the final rankings.
By combining players’ age, the average stay in the first-team squad and contract duration, the study has identified which clubs are currently in good standing for the years ahead. The results make encouraging reading for teams in the English top-flight with no less than nine Premier League outfits making it into the top 20.
You can check out the study in full here, but we've broken down the top 20 clubs in the survey below.
Top 20 most sustainable squads in Europe's 'big five' leagues, per Football Observatory
20. Everton (England)
19. Wolfsburg (Germany)
18. Osasuna (Spain)
17. Bayern Munich (Germany)
16. AC Milan (Italy)
15. Brentford (England)
14. Atletico Madrid (Spain)
13. Roma (Italy)
12. Aston Villa (England)
11. Bayer Leverkusen (Germany)
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10. Tottenham Hotspur (England)
9. Athletic Bilbao (Spain)
8. Real Madrid (Spain)
7. Newcastle United (England)
6. Leeds United (England)
5. Manchester United (England)
4. RB Leipzig (Germany)
3. Liverpool (England)
2. Real Sociedad (Spain)
1. Manchester City (England)
Analysis: It is Pep Guardiola's Manchester City that come out top of the tree in the survey. In charge of a relatively youthful squad (with an average age of 27 years and 22 days), members of the Spaniard's first-team have - on average - been a part of his set-up for three years and 116 days.
That amounts to more than a year longer than the average across the survey of two years and 109 days.
Liverpool, who are third-placed overall behind La Liga outfit Real Sociedad, also boast some impressive numbers - with Jurgen Klopp's side being the most settled of any of the sides surveyed. The average member of the first team at Anfield has been at the club for close to four years.
Manchester United, Leeds and Newcastle also rank well - although the Magpies likely won't have such a familiar look to them once the January transfer window closes. The club's new owners are expected to invest significantly in the new year, with the expected influx of fresh recruits likely to drastically alter the look of Newcastle's squad.
Outside of the top 20, however, the sustainability outlook isn't particularly good for Barcelona and Paris Saint-Germain, who rank 32nd and 33rd respectively.
Both sides are penalised in the survey for their squads having a very different look than they did this time last season. PSG have seen an influx of fresh faces, not least of which was Lionel Messi, while Barcelona have been forced to offload several stars (including Messi) in order to balance their books.
Time will if PSG are able to successfully integrate their new recruits into their side over the long-term. The size of the task facing Barcelona, though, has been well-publicised - with new boss Xavi needing to completely overhaul the first-team at Camp Nou.
Quiz: Just how elite are Manchester City?