I am very curious, not sure if I missed something here. But using Cast (yyMMdd) in a case statement throws an error
'Conversion failed when converting date and/or time from character string.'
But in a single select like below, it returns the result
select case
when ISDATE('000000') = 0 then 'False'
else CAST('950705' as date)
end [YEAR]--error on else
select CAST('950705' as date) [Year]-- 1995-07-05 (works)