What is up with them?!?!

they have beaten houston, san antonio, dallas, and the Lakers and Orlando. Houston, san antonio, dallas and La have been doing great. but they have lost to boston, portland, utah, and phoneix...and other than boston those teams aren't doing too well. Ne1 have ne explanation to this?!?! It's weird how they beat 4 of the best teams at the moment but lose to medicore teams.