Who proposed the budget for approval, hint it was Falvey. Did he think he would have a $160m payroll for the next six years, if so that was the risk he was taking. Ownership approves the budget that Falvey asks for and says he needs to meet the objectives set by ownership.
I am not sure how you know the payroll was cut for non baseball reasons. They lost $50m in tv revenue or somewhere in that neighborhood, that is baseball related. Even if it is not under his control, he needs to be aware of these situations so he can plan appropriately. He can't operate in a bubble as PBO, no business runs that way, I am not sure if you understand that.
Yes he may not have had a reason to expect such a deep cut in payroll so quickly, again what was their highest payroll before that year. You have to understand historical trends and take into consideration how those will impact future events as well. He chose to take the risk that either payroll would be stable or rise because his baseball development staff has been an absolute failure.
If I had been in his position I would have allocated those dollars more conservatively on multiple players because one player isn't going to win by themselves in baseball, just ask the Angels and Trout.