The 38-year-old, formerly of Al-Ahli and RB Salzburg, greeted every reporter with a handshake before taking his seat, composed throughout his official unveiling. Those closest to him warn that calm exterior disappears the moment he steps onto the touchline.
"I will not change my style because that's my personality," Jaissle said. "On the touchline, I am emotional, but I need to respect the box [technical area] a bit more.
"I'm a bit scared. I hope in the beginning the referees can maybe close their eyes here and there a little. I need to learn that. I had a long touchline in Saudi Arabia, so I think the GPS would be quite high if I had worn it!"
Former Hoffenheim team-mate Chinedu Obasi, who played alongside Jaissle before a knee injury ended the German's playing career at 25, is not surprised by that intensity.
"Matthias has always been very hungry," Obasi said. "He's had that leadership style and been vocal and passionate about the game. He wanted to win."
That drive will be tested quickly. Jaissle succeeds Eddie Howe, who departed last month after nearly five years in charge, a tenure that delivered the EFL Cup in 2025 and two Champions League campaigns but ended with Newcastle United slipping to 12th following a run of home defeats. Restoring that fortress atmosphere is high on Jaissle's list, and he described being shown around the stadium for the first time in vivid terms.
"We were just looking at each other with a big smile, goosebumps," he said. "Just really special. The guys here who were leading the tour told me how it feels when the crowd are there. When we hopefully play in the way they want to see us - intense football, a vertical approach, aggressive, front-footed - there is a great synergy between the fans and the team."
Players have already felt that approach during a training camp in Spain that ended with a 2-1 win over Valencia. Goalkeeper Lukas Hornicek said Newcastle want to "show the opponents that they will have a hard time against us", while defender Malick Thiaw described the intensity as "really high".
Jaissle inherits a squad reshaped by the exits of Anthony Gordon, Sandro Tonali and Bruno Guimaraes, calling the gap they leave a "vacuum". Newcastle open their Premier League campaign at home to Liverpool on 23 August.
"We are ambitious," Jaissle said. "It is why I decided to come here, but this will not happen overnight, especially when you have such a big transition phase now. If you have that synergy with the fans, the players and the staff to go there, I'm pretty sure it will be a successful story. But we need time now."