This time last season, a club-record 8-0 thrashing at Chelsea was followed by a 4-0 loss to Spurs and 3-0 defeat by Wigan, both at home, as the club plunged towards relegation.
Lambert said: "Randy phones me after every game. But I couldn't have got away with the 'we were unlucky' excuse last Christmas.
"He tells you how it is, there's no treading on eggshells. But nobody was happy about that, nobody is happy with losing.
"What did he say after the 8-0? 'How are you?' He's probably the best chairman I've ever worked with. Randy is putting in a lot of money, on and off the pitch, and there has to be that respect. Even if it ended tomorrow I'd still get on well with him.
"From day one, he told me it'd be my hardest year in management, and he was right. It could've been seen as a flippant comment but he knew the magnitude of the job, he knew it was going to be a major haul.
"Not just for one or two years, this is a big job for a right few years. We've had to strip it right back. Randy is a chairman in an exclusive club because you have to be given time. Look at the managers who have gone. It's really unforgiving.
"I never had any self-doubt, even after the 8-0. But you have to have a realism of what happened.
"If you lose your Saturday is bad and your Sunday is even worse. Then on the Monday you let it go.
"An experienced manager told me that and I took his advice. You can't let it manifest any longer."