Injury initially cost the Danish international his place in the starting 11, but since returning to fitness, Agger has failed to regain his place despite Brendan Rodgers favouring a three-centre-back system.
Despite sitting third in the Barclays Premier League and convincingly beating the likes of Sunderland, Crystal Palace and West Brom, defensive frailties and lapses in concentration have been apparent.
So, following Liverpool's lacklustre display at Arsenal, when on occasions they again appeared to cause themselves problems at the back, the time is surely right for Agger to return.
Not only is the time right, but the argument for his potential return is a strong one.
Read on to discover just three of the reasons why Agger deserves his place in the Liverpool side.
With Agger at the heart of the defence, Liverpool began the season with three wins and three straight clean sheets.
Despite a rush of blood to the head in the dying minutes of the opening-day victory over Stoke City, when he inexplicably gave away a penalty for handball, the big Dane did not put a foot wrong.
He was a colossus during the 1-0 victory over rivals Manchester United, making tackle after tackle and block after block, and he even provided the assist for Daniel Sturridge's winning goal.
The popular defender shone in his new role of vice-captain, and the job of being Steven Gerrard's understudy appeared to galvanise him in the season's early weeks.
Agger was absent from the side that dropped its first points of the season. A 2-2 draw away at Swansea brought an end the Reds' 100-percent start to the new campaign. It was no coincidence that in Agger's absence, Liverpool looked shaky at the back, and were probably lucky to leave the Liberty Stadium with a point.
Away at Newcastle, the Reds conceded from a set piece against 10 men, while in the home victories over Crystal Palace and West Brom late lapses in concentration saw both visitors net consolation goals.
Although Kolo Toure has been a revelation since his move from Manchester City, and Mamadou Sakho looks to have settled in well, seeing the name of Daniel Agger on the Liverpool team sheet will be somewhat reassuring for Reds fans.
Where Agger does rank head and shoulders above his fellow Liverpool defenders is his ability with the ball at his feet.
When he carries the ball out from the back, the Denmark captain has an aura about him similar to that of Alan Hansen during his time as a Liverpool player.
His range of passing is second to none and whether it is five yards or 40 yards, Agger's ability to find a man is a vital weapon in Liverpool's armoury.
His ability not only as a defender but as a "footballer" makes Rodgers' decision to continuously overlook him as even more of a head-scratcher. If the Reds boss insists on playing three centre-backs and insists on playing pass-and-move football from the back, then surely Agger should be one of the first names on the team sheet?
Having two of Toure, Sakho and Martin Skrtel alongside him would give Agger even more freedom with the ball at his feet and would benefit the Reds highly when they attack.
Some have questioned whether a team can deploy two left-footed centre-backs in the same starting lineup, which is what Liverpool have in Agger and Sakho.
For a team playing just two centre-backs, it is obvious how that scenario becomes a problem, but when fielding three-centre backs this shouldn't be an issue, as long as all three are aware of their position.
Never mind just being Liverpool's best ball-playing defender; Agger is arguably Liverpool's most gifted defender all round.
Not only is he comfortable in possession, but his positioning, awareness and ability in the air appear to have improved over the last 18 months.
His performances led to talk of a move to Manchester City—as reported by Jack Wilson of the Daily Star—but this never materialised, and Agger has since pledged his future to the Reds for as long as they want him, per Danish paper Ekstrabladet (h/t the Express).
As well as being Liverpool's most gifted defender, Agger is arguably one of the top defenders in the Premier League.
Vincent Kompany apart, there is nobody that stands out as being as good or as reliable as Liverpool's Danish international.
The likes of John Terry and Rio Ferdinand have been top, top defenders throughout their careers, but in the current era, it is this writer's opinion that only Kompany eclipses Agger as the Premier League's best defender.
Like Kompany, Agger oozes authority and a "thou shall not pass" attitude to defending.
For Agger, it is "win at all costs." Very rarely has a player come from abroad and had such an affiliation with the Liverpool fans.
Comments of wanting to remain a Liverpool player for as long as he is wanted and YNWA (You'll Never Walk Alone) tattoos across his knuckles have endeared him to the Anfield faithful.
What Liverpool and the fans need now, though, is Agger back where he belongs, at the heart of the Reds defence, providing a calmness and sense of security for those around him.
At the moment, Liverpool have a good side, but with Agger in there they are a better side, a more solid side, and in the Dane they have a natural born leader desperate to steer the ship, should he ever be called upon.
The sooner he is back in the starting 11, the better.
Do you agree? Should Agger return to the Reds starting lineup, or have Toure, Skrtel and Sakho done enough to warrant their inclusion? Leave your opinions below.