If we are used to Wenger's diplomacy, and there is legitimate cause for concern about the standard of match officials generally, Dunn deserved more credit that the crowd was prepared to give him.
The difficulty Arsenal's manager had in mind sprang from Derby's deployment of Lee Carsley as a policeman on Dennis Bergkamp and their determination to make life difficult for the Cup holders.
This led quickly to a heavy tackle on Bergkamp that looked fair enough and would prove so under television scrutiny.
The trouble is - and the authorities are greatly to blame for this - supporters have been introduced to the notion of a game without heavy physical contact and weighted in favour of the artist.
A personal point of view is that despite his issue of nine yellow cards and dismissing Dean Sturridge for disputing the legitimacy of Arsenal's last-minute winner, Dunn did his best to keep the game flowing.
That very few Arsenal supporters agreed was evident from calls made later to David Mellor's pompously presented Saturday night radio programme. It appears that none took into account the problems Wenger had identified when speaking about the 1-0 victory that kept Arsenal on course for a second successive Double. As for Mellor, while there is plenty of room for improvement in referees it will not be achieved by his egotistical hectoring.
Jim Smith's philosophical acceptance of another FA Cup disappointment - 30 years in the game without a Wembley appearance - was a healthy reminder that there are sounder men than Mellor in positions of influence.
"We came with a plan and it almost worked," he mused. "It's hard to lose with only 53 seconds left but that's cup football. In any case I don't sit at home thinking about how great it would be to lead a team out in the Cup final. "That's more your minds. My priority is league football, doing well in the Cup is just a bonus."
Wenger pointed out that he could be better placed to emulate last season's splendid achievements. "At this time a year ago we knew that it was possible to become champions by winning all our games and drew a First Division club [Wolverhampton] in the semi-finals," he said. "Now we need Manchester United and Chelsea to lose while we are winning."
With less than a minute of normal time left on Saturday the Arsenal manager was facing the prospect of a difficult replay. Then Bergkamp slipped Carsley's clutches to win a corner that would fall luckily for the substitute Nwankwo Kanu to turn and hook in the winner.
Derby deserved better but paid again for not being able to match defensive efficiency (third best in the Premiership) with purposeful attacking. "It's been a big problem all season," Igor Stimac, the centre-half, said. "We just don't take our chances." Smith nodded in rueful agreement. "We had opportunities in the first half but it was the same old story. After that we were always under pressure."
Unable to establish contact with their attackers, giving the ball away too cheaply when they did, Derby provided Arsenal with plenty of opportunities to press forward and Ray Parlour with room to compensate for the absence of Emmanuel Petit and Patrick Vieira. "The fact that we had 19 shots speaks for itself,' Wenger said.
Maybe, but statistics are unfair to Derby's well organised grit and a dedicated response to the plan that Smith laid out for them.
Goal: Kanu (90) 1-0.
Arsenal (4-4-2): Seaman; Dixon, Keown, Adams, Winterburn; Ljungberg (Kanu, 60), Parlour, Hughes (Vivas, 46), Overmaars (Diamora, 77); Anelka, Bergkamp. Substitutes not used: Upson, Manninger (gk).
Derby County (1-4-2-3): Hoult; Stimac; Laursen, Prior, Carsley, Schnoor (Hunt, 86); Eranio, Powell; Wanchope, Sturridge, Burton. Substitutes not used: Harper, Kozluk, Baiano, Poom (gk).
Referee: S Dunn (Bristol)
Sending-off: Derby: Sturridge (89). Bookings: Arsenal: Winterburn, Anelka, Parlour, Vivas. Derby: Schnoor, Powell, Sturridge, Laursen, Eranio.
Man of the match: Parlour.
Attendance: 38,046.Reuse content