what killed flex was that he didn't look good "opened up". his lat spreads (front and back) were really poor. everything standout on flex was related to shape and symmetry. ronnie, in 2001 at the ASC, had shape and symmetry at his all time best save 1999 plus that surreal size and far better conditioning than flex ever achieved (and if you don't believe me look at photos taken with them together, not photo A of flex and photo B of ronnie).
ronnie's lows were probably lower than any other mr olympia (2002, for one). but what you can't deny is that there are a few poses that most top pros just never looked good in. flex in his front lat spreads, dorian in a front double biceps and probably side chest. in 2001, ronnie looked incredible in EVERY pose.
yes, he had a little bit of a gut, but it wasn't what it became later and wasn't enough to spoil anything except to the most anal retentive ironagers.