The 2-0 defeat at Tynecastle by Stephen Robinson’s side in April saw the Jambos leapfrogged by Aberdeen having sat third in the table since the start of 2023 and the loss signalled the end for head coach Robbie Neilson, who was replaced by Steven Naismith on an interim basis.
After a derby defeat by Hibernian, the Tynecastle side beat Ross County 6-1 before losing 2-0 to hand Celtic the title last week after going down to 10 men just before the break when Alex Cochrane saw red.
With four fixtures remaining, Hearts is in fourth place in the table – five points behind Aberdeen, one ahead of Hibernian and two ahead of St Mirren – but Gorgie defender Sibbick revealed the negativity of last month had gone.
He said: “I think over the last few weeks, we are a completely different team compared to last month.
“Around the place everyone is more uplifted and positive. Obviously when things are tough, everyone can be a bit negative and stuff like that but since Naisy has come in, he only wants positivity.
“He has been encouraging us, having individual meetings with players, trying to get to know us a bit more. I think that has helped us a lot.
“We had a chat and he told me he could be a moaner from his time as a player but he doesn’t do it to get on to people, he does it because he wants the best for them.
“Sometimes you can’t hear him but sometimes you can’t miss it.
“It is good. He is always demanding more from us. Even when we were beating Ross County 6-0, he demanded more.
“Training has been getting better every day and you can really see it as well in our performances.
“We do have the quality so now it is just about us bringing it out and showing everyone that we do have it.”
The 23-year-old former Wimbledon and Barnsley defender admits Neilson’s last game in charge was a low point.
He said: “After that game, the boys were talking in the dressing room about how in football, nothing is ever perfect.
“You do go through those spells when you lose games and nothing is really going your way.
“We had a chat and we knew that ultimately it is down to us.
“The manager can set you up but the players have to go out there and deliver and we hadn’t been delivering and unfortunately it cost him his job.
“But now we have Naisy in and it is time for us to put things right.
“He wants us to be on the front foot. I think that’s when we play our best football, on the front foot and playing in the oppositions’ half.
“You’ve seen over the last couple of games, that is what we have been trying to do.
“Although we had 10 men for the majority of the game against Celtic, that’s what we were trying to do and we can take confidence from that and push forward for the last four games.”