@Moonwalker
David Silva was 29 when Pep took over and had shown no sign of slowing down. Rooney had come off 3 absolutely horrendous seasons for United under Moyes/LVG which had most United fans wanting him gone, it wasn't a shock to any United fans who saw the writing on the wall with Rooney that he was poor for Everton and shipped off to the MLS just one season later. Aguero was even younger than Silva. If the crux of your point is that some posters debated wether or not world class players would continue to perform at a world class level then I'm certainly not going to attribute that to Pep. Messi was world class before Pep arrived and long after. Sticking the cones out on a monday morning does not deserve a lot of credit. This isn't unique to Pep, I'm not giving Zidane credit that Ronaldo continued to perform at a world class level into his 30's either, he's a machine and Zidane had nothing to do with it.
The deadwood in their squad largely resembles the deadwood in our squad, speculative buys that turned out to be very poor. I'll point out that Nasri/Hart had certainly performed at a very high level so there is absolutely a comparison to those players held in high regard by United fans. Who exactly in the United squad Mourinho inherited has he shunned that have performed to the same level as those 2 in the past?
KDB is a case of hindsight is 20/20. First of all he was signed and remained in Genk for 6 months, he then joined Chelsea in the summer who immediately loaned him to Werder Bremen, Mourinho had nothing to do with either of these moves as he wasn't manager at the time. 2013 he stayed at Chelsea under Mourinho for 6 months before leaving, no Chelsea fans were outraged that he wasn't getting into the team ahead of Oscar/Hazard/Willian/Schurrle and no top clubs around Europe showed much interest in him either.
How many of the players that Mourinho has sold at United have re emerged as world beaters elsewhere?