There's something that always bugs me about the 'manager lost the game' framing. I think it's that it flattens difficult decisions into right/wrong, smart/stupid when in many cases it's a very narrow margin and the 'answer' is only there with the benefit of hindsight. At the time of that decision, Assad didn't have trouble with his first inning, 7-8-9 was due up and was a string of 5 straight RHH(though it was prime PH territory), the weather and game thus far had given no indication the Brewers were going to rally. Letting Assad go a 2nd inning carries risk, but so does introducing a new pitcher who might not have their control or stuff that day. If Merryweather comes in and walks a pair of guys or hits a guy and gives up a bloop the same amount of danger has been created and at least one of us wonders aloud "Assad was stretched out and got 2 Ks and a weak GB, why didn't he stay in?"
This is not to say that I think leaving Assad in was the right call, I was the first person to question it in the game thread when it happened, and I think an irrefutable mistake is not having someone warming to start the inning so Assad didn't have to face Winker. But bullpen management is making a bunch of 52/48, 55/45 type of decisions, and in a game with so many individual events that could be influential I think framing the responsibility for the loss on one or two of those creates a false impression that the manager took them from sure winners to sure losers(and therefore implies their lack of competence/intelligence).