Everyone knows "the welsh Xavi" is not playing his best at the moment. He has been losing possession much more than before. His pass completion is worse than when he started. Was he just a one hit wonder?
Fatigue
First, we have to take notice that he has appeared in 21 out of the 22 games Liverpool have played in the Premier League, since Brendan Rodgers was appointed. He could be very fit for a young man with 22 years of age, but not many people can withstand the fatigue Joe Allen has. He's played 1,719 minutes of the 1,980 that Liverpool has (87%). Only the untiring Luis Suarez (95%) and the superhuman Steven Gerrard (100%) have played more minutes than him.
Out of Position
Not only has he played a very large amount of minutes, most of them he's played out of position. With the injury of, arguably, one of Liverpool's most important player in the last couple of years (Lucas Leiva) something had to be done with the DM position. Last year Kenny Dalglish gave that role to Jay Spearing. Although a huge fan of the team and very eager to play, unfortunately he just didn't play at the level you would expect from a Liverpool player.
Then, over the summer, came Brendan Rodgers to lead the team. He knew Spearing didn't fit the part for DM, thus being loaned, and Lucas was on his way to start anew, when another unfortunate injury came upon him, with only 5 days for the transfer window to close and his mind on other players (Dempsey, Carroll, etc.). So Rodgers decided he needed someone to play the role of DM and that's where Allen came in.
The first game he didn't excel, but as the team got to learn his abilities: patience, vision and work rate, they started trusting him more until he became the "first touch" of almost all the attacks.
Philosophy
As we all know the appointment of Brendan Rodgers was huge, not only for the fans and team, but for the players. He had to teach his playing philosophy and convince all the players (and owners) this is the way Liverpool F.C. can thrive and (soon) win the Premier League.
But to teach this "philosophy" he must completely redesign how everyone played football. From the (sweeper) keeper and the attacking defence, to the always pressuring midfield and attack. He knew it was going to be a tough battle, but he wasn't alone.
Rodgers brought with him a player he coached some years ago who knew his style and who would believe in him (Borini). He also brought the best player in his last team (Allen) who not only knows the ins and outs of his philosophy, but who could (from day one) instill it in the team and could be an example to all the other players what style of play Rodgers wants and how to do it.
Liverpool F.C.
I believe Rodgers, with the help of Allen, hasn't yet finished teaching all the players his style, but you could see the fruits bearing. We can see the rise of our fullbacks, the confidence in our centrebacks, the passing in our midfield and the pressure in our attack. The best example is our captain who has hushed the people who were calling for his resignation, with his stellar performances in the latter part of the season. He has made some unbelievable strides from the start of the season and will continue to do so, because he's, amazingly, still improving.
What I want to share is that I don't believe Allen is a one hit wonder, although a rest could be very beneficial. I believe the magnificent players of Liverpool F.C. are taking the load off Allen and all of them are now starting to play the way Brendan Rodgers has envisioned it.