It seems to me that most of the things that have "gone wrong" have really just "gone as expected."
We're getting precisely nothing from our rotating cast of second basemen. No one can be surprised that that's the case. Roberts' injury, and the inadequacy of his replacements, are exactly what any informed observer should have expected.
Lack of production from our DH? Once again, who can be surprised? We made no attempt to fill the position, relied on replacement level players to fill the hole, and are getting replacement-level production. Again, as expected.
There was, oddly, some sense in spring training that we had "depth" in our starting rotation. I was always pretty perplexed that anyone thought so, given the names we were dealing with and the amount of overperformance we were counting on holding over from last year, but in any case, we're predictably seeing that we don't have nearly enough major league caliber starters in the system. (As my own mea culpa, I was quite bullish on Arrieta having a better season than last year, but it's been more of the same out of him, just as many others expected).
The bullpen? I'm not sure how many times people demonstrated that the unit was due for regression. And that's precisely what we're seeing. Again, not a surprise.
I guess I'm just not really ready to jump in and act surprised or dissappointed. We had clear weaknesses in the offseason, made no attempt to improve on them, and now we're losing games as a result. Pretty simple.