It was time for a stand to be taken. And Derry did that, turning a five-point defeat into a five-point win over the same opposition, in just over a month.
They bared their teeth here, revealed their character. Lessons were learned from the first day, pleasing their manager, Brian McIver.
"We felt we had a lot of improving to do from the last day and you can see from today that this present squad of players are prepared to work, to learn and to listen," he said in the aftermath.
"This is a very, very young side and it was obvious when we took over this side that it was going to be a long-term thing. There will be no quick-fix, this side is improving."
A ten-point turnaround against the team that ran the All-Ireland champions to three points is some upswing on the graph.
What's more, Derry were utterly dominant in the first half before a late Down surge that yielded 1-1 before half-time brought them level in time for the interval.
They needed to produce big in the second half, a period that they disappeared in the last day against the same opponents.
McIver put that in context when he said: "Second-half performances, outside of the Down game in the Ulster Championship, have been very good.
"One thing we never talked about was coming into the last game was being four or five points up and playing well.
"We found ourselves in a position we weren't anticipating being in. We were determined to learn from that and if we got on top, we were determined to press on."
They are learning fast.
As Down's Conor Laverty made a dash towards goal in the closing moments, Sean Leo McGoldrick gave him a tug and brought him to the ground. It was the type of foul that comes naturally to the very best teams, the type of teams that don't bleed big scorelines.
"2-17 the last day was a hurling scoreline," added McIver.
"We knew that we couldn't defend like that, we had to work a lot harder.
"Sometimes, that wee cynical foul, you have to do it.
"We enjoyed the last day in terms of beautiful open football, but we came out on the end of the wrong result.
"We knew we couldn't do that again."
Down manager James McCartan was obviously shell-shocked, but refused to dull the gloss of what was a great evening for Derry, explaining:"I don't want to take anything away from the Derry victory, I have too much respect for the men in charge of them," he said referring to Brian McIver and Paddy Tally, who were part of his original backroom team.
"I suppose the level of intensity that they brought to the game today showed that they were out for revenge and fair play to them, they got it."
He added, "I am not going to turn around and make a load of excuses.
"We did not perform here today the way we have in our last two Championship matches and that's disappointing for the group who have trained very hard to get a performance."
On the subject of his own future after his fourth year in charge of Down ended, he was vague.
"It's difficult. I might give an answer now that you might regret later," he said.
"These things are dealt with later on and there's no point me guessing what that's going to be."
DERRY: E McNicholl; A McAlynn, C McKaigue, D McBride; C Kielt, M Lynch [Capt], SL McGoldrick; P Bradley, PJ McCloskey; C McAtamney, J Kielt (0-2, 2f), E Lynn; R Bell (0-6, 1x'45', 1f), E Bradley (0-2), L Kennedy (0-1). Subs: E McGuckin (0-2) for Kennedy [44m], B Heron for McAtamney [53m], C McFaul for Bell [70m]
Yellow cards: P Bradley [15m], C Kielt [33m], D McBride [35m], E Lynn [48m]
DOWN: B McVeigh; D McCartan, B McArdle, K Quinn; O Costello, P Turley, R Boyle; K King, K McKernan; A Rogers (0-1), M Poland [Capt], N Madine; C Laverty, J Johnston, D O'Hare (1-4, 4f). Subs: B Coulter for Madine [44m], R Mallon for Johnston [51m], D Hughes for Quinn [55m], D Savage for P Turley [68m], D Turley for D McCartan [71m]
Yellow cards: McCartan [26m], Johnston [33m].
Red cards: McArdle [58m], McKernan [71m]
Referee: Cormac Reilly [Meath]