So the street takes Apple's figures and add 20% because they know Apple always understates by 20%, so on those figures Apple didn't do as well as they should have.
The problem is that you don't know if Apple really expected $30Bn and under-performed or really expected $25Bn and over-performed.
Apple is a public company with shareholders and has a legal(and moral) duty to actually produce honest figures. Ultimately massaging them down is just as bad for investors as talking them up.