They built up a strong record against bad teams.
Against good to very good teams they're out of their depth.
To repeat, the defending World Champions against a quality staff look like rookies getting their first look at big league pitching.
Some of this could have been foreseen, perhaps. Career bench players who had stepped up not being able to sustain that kind of performance. Gattis, a good but not great player reaching an age at which good but not great players often decline rapidly. But watching five All-Star caliber players, all healthy and at or near their prime years regress drastically all at once is Just. Fucking. Insane. If nothing changes, this is a .500 ballclub.