Liverpool restored their 13-point lead at the top of the Premier League with a commanding 2-0 victory over Sheffield United on Thursday night, meaning the Reds have now gone a year unbeaten in the English top flight.
Leicester sit second and while they are a very different side to the leaders, the pair do share one obvious trait.
Below, Goal looks at the top two's rampaging full-backs, as well as four other key tactical developments of the season so far...
Liverpool and Leicester show full-backs have become crucial playmakers
The most important aspect of 2019 from a tactical perspective was arguably the emergence of full-backs as the new creators and it has everything to do with the pattern of most matches being attack versus defence.
The limited threat from a defensive opponent means most elite full-backs rarely do any actual defending, and can instead trot forward unseen on the flanks, ready to stretch the defensive shell or simply pepper the box with crosses.
Liverpool are certainly the best example of this.
Trent Alexander-Arnold and Andrew Robertson are probably the two best players in the world in their respective positions, playing such an active role in the Liverpool attack that they have become de facto playmakers.
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By coming infield when needed, playing one-twos with the forwards, swinging in crosses from deep, or exchanging raking diagonals with each other, Alexander-Arnold and Robertson represent a new breed of outside No.10s. It’s worth noting that Kevin de Bruyne, now frequently floating out to the right for City, often has a remarkably similar heat map to Liverpool’s right-back these days.
Leicester City are the next best team at utilising full-backs, albeit in a more traditional mould than Liverpool.
Ricardo Pereira and Ben Chilwell overlap expertly, dragging the opposition out to the flanks to create extra room in the half-spaces for midfielders James Maddison and Youri Tielemans, who play a lot like Silva and De Bruyne did for City in the Centurions’ 2017-18 season.
Man Utd & Chelsea prove detailed attacking coaching is essential
The wealth disparity between the elite clubs and the rest has made Premier League football distinctly territorial; almost every match is possession versus counter, one team camped in the final third and the other sat back patiently defending.
As a direct consequence, ‘Big Six’ managers need detailed attacking tactical plans, with specific moves drilled into muscle memory, rather than relying on improvisation.
The 2019-20 season should be the seminal moment when elite clubs cotton on; Chelsea’s early season form and subsequent decline, Manchester United’s problems under Ole Gunnar Solskjaer, and the sudden contrast between Unai Emery and Mikel Arteta at Arsenal have all made it pretty clear that you cannot expect forwards to make it up as they go along.
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The opposition is now diligently and consistently trained to sit deep and frustrate. Creating space, by pulling the defence out of shape, requires high-energy pressing and complex positional coaching – the sort implemented by Jurgen Klopp and Pep Guardiola.
The great symbol of this new order is Manchester United, whose ‘pace and power’ mantra belies Solskjaer’s tactical naivety. They only perform well when allowed to play on the break, which happens roughly 10 times a season.
Chelsea are playing with genuine freedom under Frank Lampard; hence their inability to defend the transitions and the goals drying up. When roaming as they please – not unlike Lampard the player – Chelsea’s forwards spread too wide to defend counter-attack.
What’s more, opponents have worked out their attacking rhythms. Suddenly, Chelsea’s young forwards have run out of ideas.
Man City & Spurs paying for failing to refresh ageing squads
Both Manchester City and Tottenham have dramatically underperformed this season because both clubs have watched as their squads grow old together, failing to refresh when times are good. Here is clear evidence that modern Premier League clubs must act like sharks.
When modern football requires a feverish high tempo and a painstaking collective effort to break through a deep-lying opposition defence, elite clubs must be constantly moving forward. Man City’s flaws are relatively obvious.
Guardiola’s failure to find a worthy successor to Vincent Kompany backfired when Aymeric Laporte was struck down with injury, while Fernandinho hasn’t been adequately replaced in midfield and City didn’t do anything to patch up their dodgy left flank.
There have been recent signs of Guardiola finally refreshing the tactics – Phil Foden’s run of games is a welcome break from David Silva’s gradually declining performances – but it clearly comes too late to hold on to their title.
Mauricio Pochettino knew precisely the dangers of failing to reinvest but Daniel Levy wouldn’t listen. Far too many of their players were running down contracts or simply failing to listen to instructions after spending half a decade at the same club.
The result was stagnant football, and a tactical meltdown that saw Spurs fail to press or pass with any cohesion or conviction.
Sheff Utd & Brighton fly the flag for aesthetic football in an age of fire-fighters
It is sad to see Bournemouth and Southampton become deeper, reactive teams over the last 12 months as once-attacking managers Eddie Howe and Ralph Hasenhuttl give in to the demands of modern Premier League tactical battles.
Unsurprisingly, the likes of Newcastle, Burnley, Watford, and now West Ham are equally negative, and with Norwich and Aston Villa struggling badly as a direct result of playing expansively, we remain in an age of fire-fighting – for the most part.
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Brighton and Sheffield United have been a breath of fresh air, and much needed proof that aesthetic football can be played at clubs locked out of the elite. The trick to doing so – and something Daniel Farke and Dean Smith must learn – is to balance swirling possession football with a deeper starting block.
Graham Potter and Chris Wilder happily sit back, but as soon as the ball is won, they begin to recycle it rather than automatically launch a counter. But similarities between the two managers end there.
Sheff Utd’s famous overlapping centre-backs barely tells half the story of their positional switches and overloading of the flanks, while Brighton focus through the middle as the likes of Aaron Mooy and Pascal Gross drift off the wings and into space.
Everton & West Ham show long-term projects are scuppered by tactical yo-yoing
The Premier League table has rarely been so compressed with just six points separating sixth from 15th, which partly reflects the inability of the division’s middle class to find an edge this season.
By now, we should have a clear top six and a clear second tier consisting of four or five clubs, but instead the likes of Everton and West Ham are being scuppered by poor decisions at boardroom level.
Tactically, they lurch from one thing to the next, limiting their potential for long-term growth.
Marco Silva never had a chance at Everton given the squad was full of players signed for the patient possession game of Ronald Koeman or direct approach of Sam Allardyce. Similarly, West Ham are unlikely to flourish under David Moyes considering their transfer strategy had been sculpted by Manuel Pellegrini, his polar opposite.
Tottenham could be the next victims, although Jose Mourinho’s pedigree probably means they will avoid failure despite throwing out years of work cultivated by Pochettino.
Man Utd’s problems are partly the result of a similarly wild oscillation between tactical identities, and Watford’s erratic managerial merry-go-round this season has left them in peril.
If more directors of football in the Premier League were to implement an overarching strategy, then fewer clubs would lurch so dramatically between top-10 finishes and relegation battles.