The horses he beat over ten furlongs, like the German Sumitas or the US horse Behrens in the Dubai World Cup were something like professional losers. Sumitas was trounced on numerous occasions prior to the race and afterwards as well and Behrens also never won another race.
Even when he (DM) won the QE II over a mile the horses that finished 2nd and 3rd to him never came close of winning another race on numerous attempts. Almushtarak was just a huge disappointment afterwards.
In my opinion Dubai Millennium was a very decent horse, but nowhere near greatness despite being a Dubai World Cup and a Royal Ascot winner.