It is indeed the same team and the same bench as last year.
I think the 'year after' syndrome is real. It's not an excuse for bad play. But history shows it's really hard to repeat in MLB. There's some fatigue, there's psychological letdown, there's the opposite teams getting a little more psyched to beat you, there's the law of averages dictating that things aren't going to go your way like they did the year before.
Also, DD's hands were pretty well tied financially as far as making upgrades.