Uncertainty and inconsistency continues to plague Liverpool as they target a top-four finish in manager Brendan Rodgers’s first season in charge. Massive overhauls have already taken place, with many players sold to reduce the massive wage bill and the implementation of a new transfer policy of signing players that represent value with more sensible, incentive-based contracts.

Rodgers has made huge progress in implementing his pass-and-move style on the team but the Reds have experienced a disappointing season, characterized by defensive lapses that led to dropped points, such as against Arsenal and Manchester City.

Despite the recent signings of Daniel Sturridge and Phillipe Coutinho to bolster the offense, Liverpool still has a lot of work left to do in the transfer market in order to strengthen the team.

The Reds will be tasked with rebuilding its central defense this summer as 35-year old Jamie Carragher is set to retire. Also, Martin Skrtel, Daniel Agger, and Sebastian Coates are have all been the subjects of speculation suggesting they could be leaving Anfield at the end of the season.

Carragher reiterated his commitment to retiring on a high note. "I could play on for another season but the fact is the club will be buying players in my position in the summer and I can't go back to being a substitute again," he said, in an interview with the Liverpool Echo.

Skrtel could return to Zenit St. Petersburg, who recently eliminated Liverpool in the Europa League, after questioning Brendan Rodgers’s decision to leave him out of the side of late. Agger has been linked with a move to Barcelona, after Manchester City bid £20 million for the Dane last summer. Coates has not featured since starting in the 3-2 loss to Oldham in the FA Cup.

Here are four defenders that Liverpool could target as they rebuild and strengthen their defense over the summer.

Jores Okore (FC Nordsjælland)
Initially rumored to be leaving during the January transfer window, the 20-year old Denmark international has attracted attention from numerous clubs after a first season in the Champions League. He is an aggressive player, calm with the ball on his feet, and he certainly fits into Fenway Sports Group’s transfer policy of bringing in younger players. Liverpool will probably have to offer upwards of £5 million, with clubs like Fulham also interested in signing Okore.

Andreas Granqvist (Genoa)
The 27-year old defender is no stranger to the Premier League, having played for Wigan from 2007-2008. The Sweden international can provide an aerial presence as well as leadership and experience in the back. The £5 million-rated defender would certainly help bolster the amount of experience in Liverpool’s back line.

Ashley Williams (Swansea City)
Brendan Rodgers is familiar with the 28-year old having coached Swansea before making his move to Liverpool. Williams would easily fit into Rodgers’s pass-and-move strategy after completing the most passes in the Premier League last season. Swansea seem to have a price tag set at around £8million, but Liverpool may need to be prepared to pay upwards of £10 million to land the Wales international.

Angelo Ogbonna (Torino)
Ogbonna would also fit Rodgers’ template, having a 94 percent pass completion rate in Serie A and helping Torino keep the third-most clean sheets in the league. Torino has placed a £16 million valuation on Ogbonna, and Liverpool would be expected to face tough competition from Arsenal and Milan to sign him.