Harte said there was “serious tension throughout the game” as Chrissy McKaigue’s point deep in stoppage time at the end of regulation time took the game to extra-time before Conor Loftus’ late score forced penalties.
Conor Doherty dispatched the decisive penalty for Derry as Odhran Lynch saved efforts from Mayo’s Paul Towey and Ryan O’Donoghue in the shoot-out.
After winning the Allianz League Division One title over Dublin in March, Derry surrendered their Ulster crown to Donegal before losing to both Armagh and Galway in the All-Ireland series.
Victory over Westmeath in Newry last weekend ended that run of three consecutive championship defeats and kept their hopes of Sam Maguire alive but it was on the whole an unconvincing performance.
The Oak Leafers were much better in Castlebar on Saturday and, despite needing a McKaigue point to force extra-time, will likely feel they should have advanced before the penalty shoot-out.
Harte said he was proud of his players, who “looked quite confident” in the shootout.
“We found ourselves in a decent position at the start of normal time and we were in a poor position towards the end of normal time.
“It looked like we were going out of the competition after a serious fight, but the resolve was there to snatch the draw.
“The extra-time mirrored the game. It had all the appearances of going all the way as a stalemate.”
Despite his vast experience as a manager, the shooutout was Harte’s first set of penalties in Championship football.
He said it was “a lottery” and hoped the possibility of replays could be reintroduced despite a heavily-stacked football calendar.
“Many would agree that it’s not a fair way to decide a game as it becomes a bit of a lottery.
“After the game and extra-time, the replay nearly seems like the best way to do it. But with the tight dates in the calendar it’s not possible at this moment of time.”
