School A's Head is a scrupulous sort and advises his teachers to be very professional and to return results aligned to recent years. The algorithms will achieve that anyway, s/he advises and so it is best to avoid the stigma of downgrades.
Just down the road, School B's Head is a much more canny individual and judges that no-one has a clue how this will all pan out and advises his teachers to go as far as they dare in giving their students the benefit of the doubt. They go about 20% better this year than last year. Their philosophy is that whist a downgrade won't look good, this is still the best strategy for their students.
If, as has happened in the UK, the schools' assessments are not adjusted by algorithms, which Head would you rather be?