For those interested:
The ranking was taking minutes because it was scanning through some 30000
records for matches.

Since my groups are never larger than 15 and each group is contiguous in col
A, I made the sumproduct range a relative index +/- 16 -more than twice the
size of my groups and put a few (17) blank lines in at the top starting the
records from row 17.

The thing ranks the whole 30k records in a couple of secs.

Here is the revised version.

=SUMPRODUCT(--($A1:$A32=$A17),--($B17$B1:$B32))+1