Honestly the person most at fault for the sandpaper thing is Lehmann IMO. We forget - or, at least, many people around the world rather conveniently forget - that ball tampering "scandals" are rather common and rather quickly forgotten, and usually dealt with quickly and quietly. But it was that idiotic press conference after the day which threw all the fuel on the fire, being exactly the wrong mixture of admitting that they'd flat out cheated, which made people angry, whilst also obviously lying about exactly how, which made people more angry.
Which brings me back to Lehmann. Wtf was he doing allowing his captain and rookie opener out there to take the heat? Man up and front up yourself ffs, and dead-bat any questions with "we're gonna get to the bottom with this, we're working with the ICC and match referee, not going to comment further until stuff is complete". From all accounts Sutherland et al were literally asleep at the time too.