I understand Kings 1 beat Kinross 55-12, Kings 2 beat Kinross 59-5. TAS and Kinross play each year. In the last few years, Kinross has won comfortably. While TAS is a very strong Rugby school, it just has fewer boys.
TAS along with High and Grammar plays in the GPS thirds comp. TAS has been highly competitive in the thirds. For location reasons, TAS seems to play a fewer preseasons, starts more slowly and then accelerates. The Kinross match is generally the first and therefore provides an initial guide to possible TAS form.
Last year and this, the broader preseason across ISA, CAS and GPS with schools playing at different levels allows a degree of triangulation, So Kinross was weak against Kings but strong against TAS. Without having done any maths, Kinross may be more competitive this year in ISA (Kinross also improves as the comp goes on), while TAS will again be competive in the thirds.
I don't know the Kinross schedule, but TAS's remaining preseasons are against Grammar, Cranbrook and St Greg's.