Young Guru recently gave an explanation for Jay-Z's comeback album in 2006, Kingdom Come, being as lackluster as it was.  According to Young Guru, it was L.A. Reid who forced him to rush the finished product of Jay-Z's album. Guru pleaded with him to allot more time to work on the album but apparently L.A. Reid wouldn't allow it.

"Now, everything rides on this Jay-Z album. Jay goes on a world tour and goes to Africa to do his Water for Life thing. He's doing all this stuff and L.A. Reid is looking at me, like, 'We need the Jay album by the end of the year.  I'm like, 'We're not ready. I have some songs but it's not done and he's in Africa.' They're like 'If this sh*t doesn't come out, people are getting fired. I can't pay my bills, this record has to come out at this time.  I'm begging, 'Can I please push this back? He's in Africa' and they're like, 'Alright get on a plane.' I ended up meeting Jay in Taipei, Taiwan and we didn't really get to record until we got to Australia. But it's like, you're in the middle of a world tour doing soccer arenas that hold 60,000, to 100,000 people.  He's doing a show with 70,000 people and then I'm asking him to go to the studio right after that; his voice is gone. We're in a foreign place trying to catch a vibe so it's like double work. Not only did you have to memorize and do a two-hour show, now I'm asking you to be creative. This is why you get Kingdom Come."   

Source: hiphopdx.com