Liverpool slumped to a 2-0 defeat to Newcastle United on Sunday, failing to build on their recent run of good form and take advantage of many of the rest of the top-half sides not winning this weekend.It was by far the worst performance in Jurgen Klopp's opening two months in charge, characterised by poor passing, no end product and clumsy defending.Havingannihilated Southamptonin the League Cup quarter-final a few days before, and winning seven of their previous eight games in all competitions, talk had even turned to whether Liverpool could be considered title contenders this season.Had they won at St. James' Park, they'd now be joint on points with fifth-placed Tottenham Hostpur. Alas, Klopp's side failed to turn up in the north-east and instead bounced back down to earth with a bang.This was more akin to the type of performance Liverpool fans had become accustomed to under the final 18 months under Brendan Rodgersand pretty similar to the 1-0 defeat in this corresponding fixture last season when Ayoze Perez scored the only goal in a 1-0 win for the home side.The fact Liverpool's only shot on target arrived from a Dejan Lovren header in the 89th minute tells a lot about the story of the game. That he and fellow maligned Reds player Joe Allen were two of Klopp's better players explains how Liverpool's big-name players failed to show up.LineupKlopp made six changes for the Southampton match in midweek, and did so again for the team that started at Newcastle. In came Simon Mignolet, Nathaniel Clyne, James Milner, and a new front three: Jordon Ibe, Roberto Firmino and Christian Benteke.Such changes could have been anticipated; Sturridge is far from fully match fit so was unlikely to start two games in quick succession, while Origidespite his hat-trickis fourth-choice striker behind Sturridge, Benteke and indeed Firmino.With Liverpool in the middle of 10 games in 42 days before the end of 2015, Klopp has been rotating his squad in order to get the best from it. In this case, the changes didn't work, but the team he put out should have been capable of getting a result against the relegation-threatened Magpies.Klopp lined up his side in a 4-2-3-1 shape, with Milner on the left, Ibe on the right and Firmino behind Benteke. It was a similar setup to that used away to Rubin Kazan, and the same attacking quartet as used in the previous week's grinding 1-0 win over Swansea City at Anfield.That's two consecutive league games without scoring from open play, with the common theme being that Benteke, Ibe and Firmino started alongside each other.The trio are clearly not suited to playing with each other.BentekeLiverpool's standout performances under Klopp have been away to Chelsea, Manchester City and Southampton. Three games that Benteke did not start. This isn't a coincidence.Liverpool have scored five goals in the five games Benteke has started under Kloppand scored 15 goals in the seven games Benteke hasn't started. Again, this isn't a coincidence.The Belgian centre-forward isn't suited to Liverpool's style of play, especially when paired with Firmino."We didn't play any counter-pressingthe pressing wasn't good," noted Klopp post-match, per Sky Sports.Benteke's movement, or lack of it, is a major issue when he's in the side. He doesn't press effectively, and that sees the whole team-pressing fall down.Writing in the Liverpool Echo, Neil Jones comments of Benteke's performance: "Anonymous in the first halfthough he did find time to waste a very good chance during itBenteke was replaced just 16 minutes into the second. It was no surprise."There were doubts about the32.5 million signing of Benteke in the summer, with only Brendan Rodgers seemingly seeing logic in the move. Even then-Aston Villa boss Tim Sherwood noted how unsuited he was to the Reds' style of play.Benteke is clearly capable of producing a superb finish out of the blue, but his overall game is not suited to Liverpool's, and Liverpool are clearly less productive with him in the side.Benteke's role under Klopp going forward should be more as an impact substitute, as seen in the win at Stamford Bridge last month.FirminoThe other big-name signing from the summer, Firmino, was also poor. He has had his most impressive performances when lining up as the Reds' No. 9and when alongside compatriot Philippe Coutinho. He needs players around him who are on a similar wavelength and whose style fits with his.The link-up play between Benteke and Firmino is almost non-existent. By the time the two of them were subbed just after the hour, they'd only completed one pass combination between them (Firmino to Benteke, none from Benteke to Firmino).Firmino was poor, but he appears to suffer when paired with Bentekea problem not too dissimilar to Coutinho suffering when behind Mario Balotelli last season.After using this combination in two successive games, Klopp will likely think again before pairing the Brazilian and Belgian together.IbeWhile Benteke and Firmino failed to find each other, they had no such problem in finding Ibe on the right-wing. Firmino completed eight passes to the Englishman, while Benteke found the 19-year-old six times.Ibe was perceived as being Liverpool's most attacking threat, running at Newcastle left-back Paul Dummett, but his end product was extremely poor.The 19-year-old attempted five crosses on the day; none of them were successful. No wonder Benteke didn't have many chances when the delivery from wide is so poor. Ibe attempted seven passes inside the opposition penalty area, completing just three.For all Ibe's pace and enthusiasm, he is still very young and his decision-making needs time and work to develop. Running at speed may look good, but when you run into a blind alley or fail to produce anything at the end of it, it's ultimately pointless.If the plan was to deliver crosses into the box for Benteke, perhaps Milner would have been better on the right side, where he is capable of producing accurate crosses from open play (not corners).FutureWith Sturridge gaining fitness each week and Coutinho edging closer to match fitness, it could be a while before we see the combination of Firmino-Benteke-Ibe in Liverpool's attack again.Sturridge gives Liverpool a different attacking outlook, and the other attacking players look better with a player of his movement in the side. Shoehorning Benteke in isn't a long-term solution.Liverpool travel to Switzerland to face Sion on Thursday night, having already qualified from their Europa League group. Klopp could either use that as a game to rest his key players, or to build fitness and combinations for his preferred attacking players.Following that, it's league games against West Bromwich Albion, Watford, Leicester City and Sunderland before the turn of the year. Hopefully the best attacking combination can be found before 2016 is upon us.All stats via FourFourTwo's StatsZone. Click here to read full news..