A new manager can change a lot of things, but he can't make them play quick enough to break down a well organized defence if the players can't pass accurately, have poor first touches, can't outturn anyone and can't cross. Every now and then they play at a high enough pace, but everytime it looks like they finally got it, they fall back into moving the ball around slowly. It must because they're not comfortable with moving the ball around at he high pace, because they don't have the technique. That's also visible if they do move the ball around at high pace, they hardly manage because they lack the real ability to do that and be solid.
A new manager can change it by changing the style to one that suits these players: Discard any ambition of modern football and a continental style, and just hoof it forward and rush.