Over the past couple of seasons, Trent Alexander-Arnold has essentially set the standard for full-backs in the Premier League.

Not only has he been a dependable part of a generally mean defence, but his effectiveness in the final third has helped mark him out from the rest.

A dead-ball specialist, comfortable on the ball and a fine passer, many have even suggested his long-term future could be further up the pitch in midfield – comparisons in this regard with the likes of Philipp Lahm are understandable.

But the adulation has been rather quieter this season. Indeed, he has even been the target of criticism on occasion, which is an awkward position to be in ahead of a huge top-of-the-table clash with bitter rivals and league leaders Manchester United on Sunday.

So, is Alexander-Arnold genuinely having a poor season? Or is he just the victim of his own high standards?

THE KNIVES ARE OUT

With Liverpool not running away with the Premier League title this term, perhaps it was inevitable that certain players were going to start being targeted with harsh words.

The focus on Alexander-Arnold seemingly became most intense after the Reds' 1-0 defeat to Southampton at the start of January.

Many sections of the British media zoned in on the fact Alexander-Arnold lost possession 38 times in the match, more than anyone else, yet virtually all coverage neglected to mention that such statistics are heavily skewed when relating to creative players who are far more likely to lose the ball due to the greater risk involved in their roles.

In isolation, such a statistic proves little. For example, Kevin De Bruyne lost possession 34 times in a game against Watford last season, yet he also had a telling impact with an assist from six chances created. In his entire Premier League career, the Belgian has only ever made more key passes in a single match eight times.

Although focusing on that part of his game may have been unfair, former Liverpool full-back Jose Enrique acknowledged Alexander-Arnold does appear to be a little short of his best, though he is adamant dips in form are normal and could even be explained by fatigue in a packed schedule.

"All of us are humans, you all have up and downs, we don't know what's going on in his life," Jose Enrique told Stats Perform News. "It's probably going amazing for him but at some point, your performance goes up and down. It's very difficult to do what [Lionel] Messi and [Cristiano] Ronaldo have done [in terms of consistency], it's just them, no one else [can be at such a level for so long].

"At some point in the season, you always underperform. It's normal. At the end [of games] you are more tired, you have many games under your legs. We are talking about international players, players playing at international level as well, Champions League, so it's many games."

STATS SUGGEST A SLUMP

The fact is, Alexander-Arnold has been less effective for Liverpool this season, and the stats back it up.

Across all competitions, the England international has four assists in 19 games at a rate of one every 392.8 minutes. Last term, he laid on 15 in 49 games, or one every 266.1 minutes.

In the Premier League, his frequency drops to 609.5 minutes per goal involvement, having been at 186.8 last term. On the opposite side of Liverpool's defence, Andy Robertson is proving a greater threat (one assist or goal every 255 minutes).

If we look a bit deeper, Opta data tells us Alexander-Arnold is playing fewer passes into the box per 90 minutes (12) than last term (14.4), while his open-play crosses are also down to 5.2 each game from 6.7 despite average position maps showing very little change in his role or the areas he operates in this term.

But, when considering his attacking output, it is worth noting that seven of his 13 Premier League assists last season came from set-pieces – this could partly explain his shortfall in productivity.

After all, he is taking almost 50 per cent fewer corners per game (down from 4.6 to 2.7) in 2020-21, while his key passes from set-pieces is 0.9 per 90 minutes after being 1.1 in 2019-20.

One might expect this to be a reflection of Liverpool simply having fewer corners, but that isn't the case – in fact, their average of 6.7 per game is identical to last season, he just is not taking them as often.

SUFFERING FROM A LACK OF COMPETITION?

Remember, though, this is comparing Alexander-Arnold to a time when he was in an almost unstoppable side that scored for fun and did not have something of a defensive injury crisis.

If we look at his form in the context of his Premier League contemporaries this term, his critics might be a little surprised.

Indeed, his 25 chances created and 162 passes into the box are second only to Robertson (32 and 169 respectively) among defenders, while Harry Maguire is the sole defensive player with more efforts on goal (21) than Alexander-Arnold (20).

It's a similar story with respect to crosses, as his tally of 70 is the fourth highest for a defender. Again, Robertson – who seems to be thriving even more this season – tops the list with 92.

Clearly Alexander-Arnold is still performing at a high standard, though Jose Enrique suggests a lack of competition in the right-back role could be another factor in his slight dip in form.

"I believe he's 22 now, he's won everything he can win as a player but maybe he needs more competition," the Spaniard added. "I believe Neco Williams is a good player, but obviously you can't compare. That's the reality. Neco is still growing, we don't know in the future how he's going to be. That's why he [Jurgen Klopp] puts [James] Milner there sometimes, I believe, to make a point.

"Sometimes it happens as well in players, and he will come back to his best. He's so important for us. Apart from De Bruyne, I don't see any other right foot like his. He puts the ball wherever he wants with his right foot, he's incredible. But like I said, he's a human being and he's not his best right now, but I'm sure against United he will sort out everyone, I'm sure."

There's no time like the present.

Liverpool are set to stick with their threadbare options at centre-back rather than recruiting a January replacement for Virgil van Dijk or Joe Gomez. 

The Reds have played much of the season so far with midfielder Fabinho in defence alongside a rotating cast of partners after long-term injuries to their starting duo. 

Joel Matip has been limited to just eight Premier League appearances due to his own fitness issues and is facing a race to be back for a vital game against Manchester United next week. 

Academy graduates have stepped in, with Nathaniel Phillips playing three times and Rhys Williams twice in the league, while captain Jordan Henderson lined up at centre-back in Monday's defeat to Southampton. 

Although Henderson and Fabinho won nine of the 11 duels they contested between them in that match and still ranked second and third for total touches, it is not an ideal fix. 

And such issues have prompted reports of interest in Schalke's Ozan Kabak and Lille's Sven Botman, although The Athletic reported on Thursday that Liverpool will not pursue either option in the mid-season window. 

Jurgen Klopp said prior to the game against Southampton that the club would do "the right thing" this month - and that appears to mean opting against a new signing. 

Asked if he could rule out a transfer as he previewed the scheduled trip to Aston Villa in the FA Cup, Klopp replied: "I cannot say definitely we will not bring one in. It's just not likely because of the situation in the world. 

"We should not forget that the [coronavirus] situation is a tough one for all people and for football clubs as well.

"There might be some clubs with absolutely no financial problems, but this club always was and will always be - with these owners, for sure - very responsible with the things we do. 

"If the world would be in a normal place, everything would be fine, we won the league, won the Champions League, the club is in the best possible situation, and you have three senior centre-halves all injured, is that a situation where you would normally do something? Yes, definitely. 

"But we are not in that situation, so I don't know if something will happen or not. 

"We maybe could do something, but it would be a short-term solution and we don't have a short-term solution, so it's not right because it does not help. 

"We have to get through this. It's not the best moment for the whole planet, so why should it be for this football club?" 

While rotation has been enforced in the middle of the defence, full-backs Trent Alexander-Arnold and Andy Robertson have remained automatic picks. 

Alexander-Arnold tested positive for COVID-19 in pre-season and has also battled a calf injury, yet has still played 15 of Liverpool's 17 league matches. 

The right-back's performance level has dipped this season and his first error leading to a goal handed Southampton a 1-0 win on Monday. 

There was criticism of Alexander-Arnold after that match, in which he was substituted, and Klopp acknowledged on Thursday it was "not his best game", though backed the England international to recover. 

"The reason is he was out for a while with COVID and had an injury which didn't help," Klopp said. "He had no pre-season really. 

"Then with the quality he has and the situation we were in, he played pretty early. He's now getting there. 

"Physically he's fine, he just has to find his top shape again, and that will happen sooner rather than later."