I would disagree with that statement, strongly.
What was happening was that Ferrari were generally slow in practise sessions and would then go all out in qualifying. Massa was particularly guilty of this. My own take was that they were simply running on higher fuel loads and weren't pushing as hard.
There is absolutely no point in sandbagging, unless you are unbelievably confident that you will nail pole position and win the race (ie. your car can probably run at least 1s/lap quicker than your opposition's).
Sandbagging is dangerous as it prevents you getting your optimum set-up and finding the limits the speed at which you can take corners, which is what you are doing during the practise sessions.
I honestly can't think of a single reason why one team would go slow, on purpose, during a practise session (unless they are running on high fuel loads or going easy on the engine, which during pre-season tests, isnt required).
I say this every pre-season: if you are fastest in January and February in testing, then you will probably be fastest in the first few GPs of the year. This has been witnessed over the last decade or so.
