Tiwi Daramola’s double had Willie Irvine’s side well in front early on but the visitors had levelled the tie at half-time, despite Athletic’s total domination up to that point.
“We should have won it out of the park, to be honest,” said Irvine. “It could have been six or seven for us at the break and that isn’t a criticism of Arniston or an exaggeration.
“After having what felt like 40-odd shots on goal, we ended up gifting them two goals in three minutes just before the break. Both goals were from our own mistakes, which is frustrating, but I have sympathy for them after not training or playing for an extended period.”
Arbroath loanee Dylan Paterson scored just after the break to put Athletic back ahead and, with two sendings-off in between for Arniston, Paterson sealed the win with 10 minutes to go.
Irvine said: “With four of the guys coming back from Covid, I was impressed with how we kept going in the second half, as it would have been easy to lose energy.
“If we’d had a full-strength side out there, it would have been a comfortable scoreline.
“We are still without Scott Sinclair, who has scored 30-plus goals this season.”
Athletic face Edinburgh College in conference X on Saturday and Irvine believes it will be a tough match.
“They beat Syngenta last time out and, when we played them, I thought they were stuffy and organised,” he said.