Totally agree about the Metallica one, also:
Daydream Nation -> Goo : all the sonic, psychadelic landscapes, mystery and wonder gone into an ironic bullshit joke
Queens of the Stoned Age:
SOngs for the Deaf -> the new one just came out. From possibly the most significant 'new' hard-rock/heavy album of the 00s to the worst (a photocopy with less songs)
Doolittle-> BossaNova : From masterpiece to sub-REM in one album!