The Welsh midfielder divides opinion among supporters, but Brendan Rodgers is a huge fan and the more studious supporters realise the attributes he offers to the team.
Indeed, it's no coincidence that Liverpool's best performances this season came during Allen's best spell of form this season too—tough away games at Tottenham, Manchester City and Chelsea, plus home thrashings of Norwich, West Ham and Cardiff.
Allen picked up a groin injury late on in the defeat at Stamford Bridge and has made two sub appearances against Aston Villa and West Brom as he returns from the injury.
What Liverpool have been struggling to achieve all season is control in midfield—an oddity given Rodgers' desire for such possession football.
However, during that pre-Christmas spell of games, when Allen lined up alongside fellow dynamic midfielders Jordan Henderson and Lucas Leiva, the trio gave Liverpool that midfield domination.
The trio—all mobile, technically solid players—compliment each other expertly and allowed the attacking trio of Luis Suarez, Raheem Sterling and Philippe Coutinho to combine in the final third. Liverpool's midfield had natural balance and thus the whole side benefited.
BR: “Having Joe Allen back is a real plus for us as before he got injured he was outstanding."— Viktor Fagerström (@ViktorFagerLFC) February 1, 2014
Last Four Fixtures
The last four fixtures have seen Steven Gerrard employed in his "new" defensive midfield role. This article isn't for debating the merits and faults of that decision, but Liverpool have failed to have any sort of control in any of those four fixtures. Allen's return can help with that.
At Stoke, the roller coaster of a game, Liverpool were far from in control of midfield. The next match, at home to Villa, Rodgers' side were comfortably overran in midfield before Lucas Leiva's half-time introduction. Against Everton, the Reds played on the counter attack.
And on Sunday, at West Brom, again the midfield control was severely lacking.
After impressing at the tip of the midfield triangle in the derby, Philippe Coutinho struggled against the Baggies, while Jordan Henderson—who has featured in all 28 of Liverpool's games this season—looks like he could benefit from a rest.
Rodgers knew that he needed to gain control of possession to stifle the home side after they began to press Liverpool, but his introduction of Allen came too late, Kolo Toure's error arriving seven minutes before Allen was introduced.
It isn't just about what he offers on the ball, but more so off the ball; he is in the correct position to receive the ball and is able to play out into the correct areas to move the opposition.
Take Toure's mistake on Sunday. Had Gerrard actually moved once Toure received the ball under pressure, Toure would have had the captain to pass to. Gerrard, instead of moving three yards forward or back in order to create the angle for the pass—something Allen is excellent at doing—stays still and instead just points to play the ball back to Simon Mignolet.
Gerrard isn't dynamic enough for the role, Allen is.
Next up for Liverpool are Arsenal at Anfield—a fixture that saw Allen as the "standout performer" (Daily Telegraph) for the home side despite a 2-0 defeat early last season.
Back in those early days of Rodgers' Anfield reign, Allen was playing as the holding midfielder in the manager's three-man midfield and he collected the Liverpool FC man-of-the-match award in both the opening home fixtures, against Manchester City and Arsenal.
What Allen provided wasn't goals or attacking influence, but he was key to ensuring Rodgers' tactics were able to be implemented and that crucially revolves around the midfield.
With Tottenham, City and Chelsea all to visit Anfield in the latter half of the season, Allen's influence in midfield will be key to Liverpool having some control of the game in the key areas.