Before Magnezone was OU, why was it BL? It doesn't seem like it'd be too threatening in UU as there aren't as many steels aside from Forretress, Empoleon and Aggron - the latter of which beats it - and the fact Magneton is B - used to be B- - seems to speak volumes to me, not to mention that Magnezone doesn't particularly stick out as a powerhouse among many big threats in UU. Is there something I'm being really stupid about and missing, or...?
It was BL due to it being able to 2HKO almost the entire tier with Specs Analytic, if I'm not mistaken.
Edit: Read this http://www.smogon.com/forums/threads/uu-tiering-system-voting-records.3520708/#post-5439662