The Premier League season is barely halfway over, but the title basically could be decided this week. Right now, Liverpool has a 7-point lead over Manchester City at the top of the table. The two teams face off Thursday at Etihad Stadium in Manchester, and a Liverpool victory would result in a likely insurmountable 10-point gap.

Only two weeks ago, Liverpool’s lead was just 1 point, 45 to 44. And at the beginning of December, it was Manchester City in front, with a 2-point cushion. But the holidays were a nightmare for City. Manager Pep Guardiola saw his team lose easily winnable matches at home to Crystal Palace and away to Leicester City, while Liverpool swept its holiday fixtures. If you had watched these events from the perch of FiveThirtyEight’s Soccer Power Index projections, you would have experienced severe whiplash. Not only did Liverpool open up a lead out of nowhere, but the projections remained extremely bullish on City’s chances right until the bottom fell out.

Before City went into a slump, what made the team such a dominant title contender? And what happened to drop its chances so dramatically?

Through October and into November, Manchester City’s underlying statistics were otherworldly good — they had analysts wondering whether this might be the best team in Premier League history. The Soccer Power Index projections are based on precisely these underlying numbers, and they reacted proportionately. The expected goals differential — the difference between expected goals for and against — shows Manchester City more than plus-2.5 per match in October and solidly more than plus-2.0 right until mid-December, based on data from analytics firm Opta Sports.

This slowdown appears to be driven by two related factors: a decline in performance by the team’s aging midfield stars and injuries to key players.

During Manchester City’s record-breaking title season in 2017-18, the team’s preferred midfield used Fernandinho as the defensive midfielder at the base and David Silva and Kevin De Bruyne as “free eights,” more advanced midfielders with the freedom to make runs in and around the penalty area but who are ready to lead the press should possession be turned over. The trio played together for more than 50 percent of City’s minutes in the league, and at least two were featured in more than 90 percent of the team’s minutes.

De Bruyne has been unavailable most of the year because of two successive knee injuries. He has not fully recovered, missing the Southampton match this weekend. With the Belgian playmaker out, Man City has been able to play its first-choice midfield for only 35 total minutes this season, compared with more than 1,800 last season. And Silva and Fernandinho, as important as they are to City’s chances, are 32 and 33 years old respectively. Both have needed rest, and both suffered muscle injuries in late December. In Man City’s losses against Crystal Palace and Leicester City, neither Silva nor Fernandinho made the starting lineup.

Man City’s biggest problems, then, seem to boil down to personnel. The heavy workload already had strained Fernandinho in his difficult role as the lone defensive midfielder, and then injuries left Guardiola with almost none of his preferred midfielders. Ilkay Gundogan and Bernardo Silva are good players, but they have not been able to properly replace Fernandinho and David Silva.

This is good news for City fans: Fernandinho and David Silva are back, and they dominated Southampton en route to a 3-1 win. De Bruyne may even be ready to join them Thursday. We should expect a Manchester City with a fit midfield to be more than good enough to win a home match against Liverpool and keep the title race going.

At the same time, Man City fans still have cause for concern. Given the ages of David Silva and Fernandinho, another slowdown or injury is hardly unlikely. And with City looking at a deep run in the Champions League, the team’s performance level cannot be expected, on average, to remain in its early season stratosphere. Expected goals differential still shows City as the best team in the league, but the margin of its advantage over Liverpool from October is unlikely to return.

This gives Liverpool every chance at its first league title in decades. And the Reds are here because they have become the smartest-run team in England. Liverpool lost a key creative midfielder, Alex Oxlade-Chamberlain, to a serious knee injury at the end of last season. But high-level replacements were already lined up. The club had reached an agreement with RB Leipzig the previous summer for the transfer of creative dynamo Naby Keita, and over the summer Liverpool added another creator in Xherdan Shaqiri as well as Fabinho for defensive midfield depth. Keita has struggled with his fitness; for a player who was clearly the best dribbler in Germany, his 0.2 progressive runs per 90 minutes show that Liverpool still hasn’t seen his best. But the Reds’ clever business strategy means they could weather a slow start. Shaqiri has been revelatory — with six goals, two assists and a team-leading 4.1 progressive passes per 90 minutes — and Fabinho has settled in solidly at defensive midfielder.

Liverpool has made steady improvements as the season has gone on. The Reds continued a trend I noticed last year, in which the team has gradually pulled back on its high press while improving defensively. This year, while the team’s mere eight goals conceded reflects some good fortune, its average of 0.81 expected goals conceded per match (about 16 expected goals allowed total) is the best of manager Jurgen Klopp’s tenure. And Liverpool has done it with its least aggressive midfield press of the last four seasons, breaking up less than 49 percent of new opposition open-play possessions within three passes.

Klopp has acknowledged this somewhat more pragmatic style as a tactical choice to get the most out of his team over a full season. Against Manchester City away, coming off a full slate of holiday fixtures, Liverpool will need to draw on this newfound defensive pragmatism. City should look to dominate possession, but Klopp’s tactical developments at Liverpool have helped build a team that can control matches without the ball. And if City’s aging midfield makes a misstep or if Fernandinho finds himself isolated or out of position, Liverpool’s devastating forward three of Sadio Mane, Roberto Firmino and Mohamed Salah will make him pay. The quality of Liverpool’s attack, especially in the open field on the counter, is such that even a fully recovered Manchester City could be caught out and defeated.

City is favored on Thursday for good reason. But over the full season, City looks more fragile than Liverpool, which has been built into a deep and tactically variable unit with smart analytics and coaching. If Man City can maintain the fitness of its 30-something midfield stars, it has the advantage, but that’s a big “if.” With just more than four months remaining in the season, another dip in form or fitness from City’s midfield is likely, and that plus a lead of at least 4 points would probably be enough for the Reds. Klopp’s side could put the title to bed Thursday, but even if City gets the win, Liverpool should still be favorites to lift the trophy.

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