R. Star wrote:
Pretty much stated. They redesigned the uniforms for First Contact and to maintain continuity they had to switch the DS9 crew over. Which was funny since you'd see the extras in the old uniforms for a number of episodes until they had enough made for them. Heck, the Admirals didn't get new uniforms until season 6.
IIRC, there were even extras in TNG uniforms in the finale.