In 1995, Julian Jackson won the vacant WBC middleweight belt (McClellan vacated it to fight Benn at super middleweight). Since then there was always someone who held that title and didn't vacate it. I'm ignoring the farce that the WBC made with Martinez (in order to give JCC jr a belt by robbery against Zbik). 21 years ... that's pretty long. Julian Jackson -> Quincy Taylor -> Keith Holmes -> Hacine Cherifi -> Keith Holmes -> Bernard Hopkins -> Jermain Taylor -> Kelly Pavlik -> Sergio Martinez -> Miguel Cotto -> Saul Alvarez I don't know another current title holder whose belt wasn't dropped in the last 21 years. Is there any other title that wasn't vacated for more than 20 years?
Actually Cotto dropped it right before their match because he didn't want to pay sanctioning fees. So Cotta beat him to it. A pair of pussies.
The belt had been dropped by Maravilla when HBO didn't want Zbik, and then won in a disputed win by JCC Jr against the same Zbik. That's how Jr got his paws on it. Then later Cotto vacated it again which should have led to Golovkin becoming full champion already, but they kept the now vacant belt in play for Canelo. So vacancies have happened very recently. A mandatory fighting for the belt hasn't happened since 2010 though.