The win relieved mounting pressure on Kenny and secured Ireland a first win in the UEFA Nations League, with former Ireland defender Breen toasting a sparkling performance capped by goals from Alan Browne, Troy Parrott and a screamer from Michael Obafemi.
"This was a classic Irish performance," Breen told Premier Sports. "This manager talks a lo about playing football, but they mixed it up perfectly and were not afraid to play it more direct at times.
"It's the best Ireland performance we've seen under Stephen Kenny by a country mile and the manager got it right by going with Jayson Molumby and Jason Knight in the midfield as they were both outstanding.
"Molumby would have been disappointed to get left out in recent games and did he take his chance when it came? Absolutely, he was outstanding and that goes for every Ireland player. It was a privilege to see this performance.
"They got in Scotland's faces from the first whistle, got the crowd involved and it was great to see.
"Winning that midfield battle was the key to victory and the goals were the icing on the cake. We have been waiting for a performance like this from Stephen Kenny's Ireland now they have to kick on and build on this."
Former Ireland captain Kenny Cunningham suggested Ireland's desire was a few steps ahead of Scotland, as he saluted the Ireland performance.
"We have been looking for the introduction of an extra player in midfield and we had that in this game with Jason Knight and Jayson Molumby either side of Josh Cullen in the midfield," said Cunningham.
"The most pleasing aspect of the performance for me was the defensive shape and solidity we had.
"Then we had that bit of pace up front with Troy Parrott and Michael Obafemi and Scotland couldn't deal with it. It was an outstanding Ireland performance.
"I enjoyed the partnership of Parrott and Obafemi. It was the first time in a while that we have seen two Ireland forwards linking up so well together and it gave us a real threat.
"Scotland went into their shell. They have some real leaders in that dressing room, but they didn't fancy this and I was surprised to see that, but Ireland deserve credit for making them play the way they did."