Short answer 'no', long answer 'yes'.
Blackwell was massively unlucky to be sacked two games into a season, after a draw and a loss to two promotion contenders. He was also unlucky that after the play off failure, the budget was slashed yet the objective remained the same; play-offs minimum. But it was at this time he made more mistakes in the transfer market such as Simonsen, Ertl and Taylor are 3 of the worst players I have ever seen at United.
On the flipside, like you said, Blackwell inherited a strong squad with plenty of talent at his disposal. Thinking about players such as Naysmith, Morgan, Killa, Walker, Ugo, Naughton, Speed, Gillespie, Cotterill, Sharp and Beattie makes me drool with envy of how good we had it! His job was fairly simple after the dull, uninspiring spell that Bryan Robson caused; motivate that group of players and get the best out of them and he did. Towards the end of 2007/2008 season we were sensational and the season after we were unlucky to be pipped by Birmingham to the 2nd automatic spot. But with one of the largest budgets in the division at that time, you could still label that year a failure.