practise the science of overstatement to a ludicrous degree and succeed

[Vladv1]

"By now Highway To Hell was on its way to becoming the biggest-selling AC/DC album yet. For once, reviews in the British music press were uniformly good, though still somewhat grudging, as if ashamed to be enjoying such anti-intellectual, unashamedly populist fare. The headline in the NME proclaimed in upper case: ‘THE GREATEST ALBUM EVER MADE’. Then in much smaller type underneath: ‘(In Australia)’, then describing AC/DC as ‘a band who practise the science of overstatement to a ludicrous degree and succeed’. Even their staunch Sounds ally, Dave Lewis, while giving a general thumbs-up to the album, felt obliged to point out that ‘Highway To Hell marks no new adventurous groundbreaking for AC/DC.’ Nobody picked up on the extravagantly lush, even intricate sound their new producer, Mutt Lange, had gifted them. Nobody grasped the sonic leap forward they had made. Certainly nobody predicted a big hit. Merely that more of the same seemed of itself a strong enough card to play at a time when the new wave was impatiently pushing, sometimes to its own detriment, at musical envelopes every week".
Mick Wall, "Hell Ain't A Bad Place To Be".
What does "practise the science of overstatement to a ludicrous degree and succeed" mean in other words?

 

[SoothingDave]

Do you know what understatement is?

 

[Rover_KE]

… and what ‘ludicrous’ means?