[zlopikanikanza]

the Red Bull rear wing is steeper also so gets a greater advantage from using the DRS, which is unliimited in Qually, so gain more. In the race when its use is limited (and they are usually in front) that advantage is negated. The McLaren has the opposite philosophy, meaning that it is quicker in race trim without the need for the DRS, but the gain is less when opened.

Red Bull also have a less effective KERS system (when its even working) which is less use for them in the races, but enough over the one lap in qually

add in the off throttle diffuser blowing being better and the fact that their higher downforce configuration actually shortens the life of the Pirellis in the faster corners, and you have a car that is devastating over one lap, but slightly compromised over a race distance, alowing the field to be closer (by field i mean McLaren and occasionally one ferrari and/or one Merc)