To me the bigger issue with Scioscia isn't years like the last couple where the team is just bad (though he isn't helping at all), it's years like 2012 and 2015 where the team was good (especially 2012, look at that roster) and should have made the playoffs, yet didn't make it. There is absolutely no excuse for the 2012 team not winning the division. The 2014 team's performance in the playoffs as well was inexcusable.
Scioscia's poor bullpen management and loyalty to veterans cost the team in those seasons.
Any other major market team would have fired him on several occasions by now, maybe even after 2010 or 2011's failures.
He was once a great manager in the 2000's, possibly the best in baseball. He began to grow complacent in the late 2000's when he became infatuated with Jeff Mathis, the suicide squeeze in the 2008 ALDS was the first big sign. It was time to turn the page a long time ago. Anybody who will miss him needs to let go of the past.