If it wasn’t clear Matthias Jaissle’s honeymoon period at Newcastle was over, it sure is now.Jaissle oversaw the Magpies’ third loss in their last four games on Saturday against Aston Villa at St James’ Park, prompting a chorus of boos at full time.Jaissle is learning just how unforgiving the Premier League can beAFPRubbing further salt into the wound was the fact Johan Manzambi, who looked destined to join Newcastle only for Villa to hijack the transfer in the summer, scored the only goal of the contest.It was a worrying performance from Jaissle’s side as they carved out just one shot on target courtesy of centre-back Sven Botman.The lack of cutting edge in the final third had ex-Magpies defender Warren Barton on edge, as he believes Jaissle has ‘got to start learning quickly about the Premier League.’Warren Barton’s verdict on Matthias Jaissle“There is a concern because to have one shot on target at home against Aston Villa is not good enough,” Barton said on talkSPORT Breakfast.“I know they’re a good team and maybe with the international break he’s not had a lot of time on the training field. But we don’t look like scoring. “And when you concede goals like we are from crosses, from combinations on the edge of the box, it is a concern.”Newcastle’s inability to fashion high-quality chances was also apparent in the 4-1 loss to Coventry last Monday.Jaissle’s side boasted 65 per cent possession and registered 18 shots, yet only breached Carl Rushworth’s goal just once.The tactical tweak Matthias Jaissle must makeWith the attacking approach under Jaissle evidently struggling to click into gear, Barton believes it’s time the German, who replaced Eddie Howe in the summer, gets back to basics.“We need to start sticking together and we need to grind out results,” Barton said.Newcastle have scored more than one goal just once in their last five fixturesGetty“I think Matthias wants to be a coach that wants to be on the front foot, wants to hurt teams, but the Premier League is ruthless. He’s getting punished. “Every time we go forward, they look isolated. It can be a lot of pressure for these players to handle. “It’s great when it’s going well, but you need to be brave when the boos start going.”Barton also believed a bright start under Jaissle, where Newcastle were unbeaten from their opening five fixtures, may have ballooned expectations.“But we know what the Premier League can be like,” Barton added.“It can be ruthless and unforgiving for teams and for coaches.”Jaissle’s next opportunity to arrest Newcastle’s slump comes next Sunday against Crystal Palace, who were thrashed by Brighton 5-0.