His worst move might have been Didi. Certainly not malpractice at the time, and nobody could have known he would be so poor at the plate, but the defense has been terrible, and if he'd signed Galvis he could have done better than Bradley (or bought another reliever or OF in addition).
With the payroll the team has, "just go .500 and see what you need at the deadline" is probably not supposed to be the plan, but it's also not a bad plan. I'm sure Dombrowski didn't expect all his pitchers to work out (including Vince) but things would have been a lot better if one of them had.
That's what Cutch and Didi were supposed to be. Right now I'd say the problem is the team has some strong leaders, they are just leading the team in a bad direction.