At one level there's some truth in his article - the last step is the hardest. As optimistic as I am for next season, there's still a lot of work to do to actually win it. However if Carragher thinks that Liverpool's squads under Houllier and Benitez were comparable to United's of those eras, then he is seriously deluded.
When Houllier finished 2nd in
01-02, his squad was big and well balanced, but very few of those players were as good as either United or Arsenal's first teams of that era and most were far behind. When Benitez finished 2nd in
08-09 he had a really strong spine - Mascherano, Alonso, Gerrard & Torres - but he had to fill out the first team and squad with mediocre players like Benayoun, Riera, Arbeloa, Aurelio and so on. Liverpool fans might argue that Torres was the best striker in the league back then, but no-one would argue that Torres, Robbie Keane, Dirk Kuyt and Ryan Babel were even close to Ronaldo, Rooney, Tevez and Berbatov.
When SAF started a season with a level playing field in terms of personnel - as he did vs Arsenal, then later Chelsea, then later City - the seasons were actually very close. SAF usually edged them, but those other teams won titles too during their periods. But at no point did Liverpool go into a season back then with the best squad, whatever hyperbole Liverpool fans might have spouted at the time.