It was terrible from Furlong, but he's a very poor footballer, so it's not so surprising that faced with an open goal and the luxury of the time to take a touch that he can't even manage to hit the target. Even with someone as limited as Charlie Austin we would have beaten Derby comfortably.
Austin most likely wouldn't have been in that position though, he's not a RWB.
In fact, none of the chances fell to forwards and that's something that needs addressing. When we started playing football, our two best finishers were not on the pitch.
If we continue to play like we did second half, from the start, when the likes of Grant and/or Robinson are on, they will score.
As it was, we could still have won comfortably, barring an excellent/jammy goalkeeping performance and poor finishing.
If we had carried on in the same vein, in the second half, then I could fully understand all the criticism, but, for me the changes we made, at half time, render the "lack of Plan B" argument moot. The second half was Plan B and, if we'd have took one of the many chances, it would have worked.