That's true !
I had about 4 shining pokemon in the silver game + plus one had didn't catch, it was at the beginning, a blue ditto, i had only five pokeballs and one greatball...
I didnt catch it...
...hum...And i only catch one shining pokemon in the ruby version( a gold barboach)
+ the one i killed, ( **** critical hit)...
I have played about 400 hours in the ruby game and 500 in the silver one(could be this)...But like you, i think they lowered the ratio...