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Of all the troubles Jurgen Klopp might have imagined his side would be facing midway through a season where their defence has been decimated, a shortfall of goals was perhaps not high on his list.

A side that has scored 84, 89 and 85 times in their last three Premier League seasons are finding the net rather harder to find of late, something which has even their manager befuddled. "There's no easy explanation. We always missed chances," said Klopp. "You have to try to ignore the talk around, because that's how it is – it's football, everybody wants to see goals, if you don't score goals everybody talks about it."

Klopp is indeed right that it is the topic du jour around Anfield.  A three game goalless streak might suggest an attacking malaise where Liverpool are concerned but some caveats are required. Klopp's side remain the Premier League's top scorers by a margin of three goals. As Crystal Palace can attest, when the champions are in the mood they can rack up goals at will.

And yet since that 7-0 obliteration of the Eagles before Christmas, Liverpool have scored one goal in four Premier League matches and have gone 348 minutes without finding the back of the net. Not since the 1999-2000 season have they gone four without a goal but Burnley comes to Anfield next, a side whose modus operandi has been to snuff out easy chances and challenge their opponents to score from low percentage shots if they are to win.

Sean Dyche's side do so thanks to the sort of settled, consistent backline that propelled Liverpool to their title triumph last season and whose absence seemed likely to derail their defense of the crown this term. It has been to the credit of Klopp and his players that the absence of Virgil van Dijk and Joe Gomez has not led to opponents finding the net with greater regularity. The Reds have conceded four goals and are allowing fewer shots on target per game since losing the latter in mid-November. Rather, keeping that defensive solidity intact has had a significant impact on their attacking approach.

The cumulative effect of defenders' absence

Aside from the numerous defensive challenges that come from losing the world's best central defender, taking Van Dijk out of this Liverpool side immediately forced a reappraisal as to how the champions built their attacks. The Dutch international would often be the most effective at moving his side high up the pitch with raking balls out to the flank. Only Trent Alexander-Arnold completed more passes into the final third last season and no-one made more than Van Dijk's 171 to take the Reds from their own half into prime attacking position.

Compounding the simple absence of Van Dijk is how it has forced Klopp to completely reconfigure a midfield that clicked perfectly into gear last season. Fabinho has excelled as a center back but Liverpool have missed the steadying hand at the tiller he was from his anchorman position. Or, more precisely, they have not so much missed that as what the Brazilian's replacement in that position brought higher up the pitch.

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As we noted last week, Jordan Henderson has proven to be a more expressive and creative passer than he is given credit for and last season was crucial at progressing Liverpool up the pitch with his passes out wide to the advancing wing backs. This season he has needed to protect a hastily put together backline that has often included one or more youngster and has often been asked to do so alongside a midfield partner. 

With Thiago Alcantara also sidelined it has left Liverpool without someone to stretch play in behind teams, an advanced midfield duo of Curtis Jones and Georginio Wijnaldum (or often only the latter) offering plenty of dynamism but less passing range.

Even before Henderson was moved to center back in the defeat to Southampton he was operating notably deeper and more centrally than the inside right position he had been playing in last season. With the defense needing such support that spot has instead been filled by Mohamed Salah.

Trent's troubles

The natural assumption might be that it would be Trent Alexander-Arnold who would step into those spaces, so assured is he in possession that it was suggested early in his career that he would eventually graduate to a central midfield role. Instead the 22-year-old has been anything but the progressive force Liverpool needed this season, partly due to his indifferent form and partly by design.

What was swiftly apparent in the 0-0 draw with Manchester United, where Klopp added Xherdan Shaqiri to his midfield three, was that Alexander-Arnold would not be allowed to advance up the pitch as frequently as he did in the title-winning season. Instead the No.66 formed a back three with the repurposed Henderson and Fabinho when Liverpool were in possession, Klopp clearly reasoning that his leading assist provider last season was more needed to repel the visitors' counter-attack.

It may have kept United at bay but the absence of Alexander-Arnold clearly stunted Liverpool's attacking play. Shaqiri and Mohamed Salah gave them two left-footers on the right flank, both drifting into similar positions without anyone to stop the left-back from following them inside. The former created just one chance in the game whilst the nominal right-back did not manage one, the first time since July he had gone a full 90 Premier League minutes without providing a shooting opportunity for a team-mate.

His change in attitude was rather typified in the 16th minute at Anfield when, with Fabinho and Bruno Fernandes battling for a clearance just inside the United half, Alexander-Arnold opted for the most safety first of plays, volleying the ball all of 60 yards backwards in the direction of Alisson. Last season's man would surely have taken the ball and driven down the right flank.

Yet this season has seen Alexander-Arnold diminished in numerous ways. The explanation for that may well be a start to the season curtailed by illness and a calf injury. "The reason is he started, was directly out for a while with early Covid, then had an injury which didn't help, so he had no pre-season really, if you want," said Klopp earlier this month.

Though the Liverpool boss believes an upturn in form is around the bend there has been little evidence of him recapturing last season's levels in attack. This season he is completing fewer crosses from open play per 90 minutes (from 6.74 to 5.29), in chances created (2.47 to 1.65) and expected assists, a metric which assesses the likelihood of a player's passes turning into goals for the player that received them. In that case in particular the decline has been precipitous from 0.27 to 0.16 per 90, albeit the former was an exceptionally high figure for any player let alone a full-back.

What crosses he does deliver do not seem to be coming with the same variety as last season. As the graphic below indicates, he is getting to the byline and the edge of the box more infrequently and putting more balls into the box from level with the penalty area. Compared with Andrew Robertson, whose form has not suffered to quite the same extent, he does not get into prime crossing positions as frequently. 

Where Trent Alexander-Arnold has been delivering crosses from in the 2019-20 and 2020-21 seasons. Note the lesser variety of positions from which he has crossed so far this season. Opta

Equally one of the key attacking weapons the full-back pair have utilized in Liverpool's rise has been deployed far more infrequently this season. One of the Reds' killer moves last season had been to suck defenders towards the dual threat of Salah and Alexander-Arnold on the right flank and for the latter to spread play immediately to Robertson on the left. It was as hard an attacking move to stop as there was in the Premier League but this season Alexander-Arnold is making 14 percent fewer passes to his partner in crime.

It may be that the absence of the full-back tandem is as damaging a factor in Liverpool's recent attacking malaise as anything. There was a stage early last season where managers such as Unai Emery opted to flood the center of their defense to try to repel the trident of attackers only to find themselves beaten by the unerring accuracy of Alexander-Arnold and Robertson from wider areas. If that tandem are even half as effective then suddenly the approach that United reprised on Sunday becomes infinitely more likely to draw success.

Salah's new role

With their midfield rejigged and at least one full-back struggling for form, attacking impetus has to come from somewhere else, especially down the right but perhaps across the team. Salah, Sadio Mane and Roberto Firmino have always had creative muscles that they could flex at will but the best Liverpool teams have not required this front three to carry much of a burden outside the final third.

That was particularly the case for Salah last season, for whom 21 percent of his touches last season came inside the opposition penalty area. He was a goal scorer supreme, largely free to polish off the opportunities that came his way with Henderson and Alexander-Arnold doing the leg work down the right. Even though he ended the season with more assists the Egyptian was beating fewer players, delivering fewer crosses and playing fewer key passes. That makes sense. Why have one of the game's most deadly finishers laying on opportunities when he is the one you want finishing them off.

This season that has changed somewhat with Salah forced to drop ever deeper in pursuit of the ball, as his heatmaps indicate.

Mohamed Salah's touch maps for the 2019-20 and 2020-21 seasons. Note how this season Salah has seen far more of the ball in deep central positions, usually occupied by Jordan Henderson or Trent Alexander-Arnold. Opta

Equally, because he is operating from deeper he is now taking 28 percent of his shots from outside the box having not even attempted 17 percent the season before. The same is true, to a lesser extent of Mane and Firmino. Without a flawlessly functioning system behind them the front three are having to do more and deal with less – it is notable as well that those two have been taking far more headed shots than in years gone by. If the full-backs are having to put in more crosses from low percentage positions then naturally the likes of Firmino and Mane will be attempting more headers and fewer high-percentage shots on their strongest foot.

Brilliant as this front three might have been over the past few years they can only manufacture so many good opportunities for themselves. Liverpool still have the quality to retain possession and advance into shooting positions, hence why they average almost exactly the same number of shots as the 15.55 they registered last season. The issue is that they are not the same high-probability looks a year on.

How much can that change with the current personnel? An uptick by Alexander-Arnold will help but so long as Gomez and Van Dijk are out Klopp is still going to have to compromise his vision elsewhere. A full-back will have to shore up the defence, for the toughest opponents a two man midfield pivot will be needed. The introduction of Thiago, so exceptional for the first 20 minutes against United, might mitigate some of these structural issues though his manager would surely agree that even a playmaker as talented as the Spaniard cannot be as good as a perfectly implemented system. Until this team are not having to cover for a jumbled together defense this might be as good as it gets.  

And yet for these difficulties Liverpool have still created enough over their four game blip to win each of these games. Between them Firmino, Salah and Mane have had 32 shots on goal in that time with a combined expected goals value of 4.46. They have converted those chances to just one goal. As good as it gets for the champions is still a fair way better than many other teams can manage.

CBS Research and TruMedia assisted with this article.