The 27-year-old Pole hinted he'd been given the cold shoulder by former boss Csaba Laszlo during a spell on the sidelines due to injury before returning to his homeland to try and kickstart his career with a loan spell at Arka Gdynia last season.
But, since returning to Tynecastle in the summer and earning a new three-year contract, Mrowiec said he'd felt nothing but warmth thanks to the much different management style of Jim Jefferies and his backroom staff of Billy Brown and Gary Locke.
"When I was out injured I felt a little bit in the back," said the man who arrived in the Capital in 2007 after spells with both FC Vilnius and FBK Kaunas in Lithuania. "And it isn't nice when the manager doesn't come and speak to you or asks how you are doing.
"I now have better contact with the coach and staff than I did before. Jim Jefferies, Billy Brown and Lockey talk to players. They know everything about us. It is like having friends in the dressing-room and that is a big difference."
Being clear of injury is another difference for Mrowiec from that unhappy spell under the former manager and he's relishing the role handed to him this season by Jefferies.
While the likes of David Templeton, Rudi Skacel and Kevin Kyle have been thrilling the fans by banging in goals, he's been one of the players laying the foundations that the side's excellent run has been built on.
"The main difference for me this season is that I don't have any injuries and I am able to play. I can help the team and this is very different for me," he added.
"The manager has also helped because he has given me some credit. I can play now and I have the chance.
"When I was in Poland last season, someone from Hearts phoned me and asked if I wanted to come back. I said, 'yes, of course'.
"After I came back, the gaffer was able to see me play for the first time and he said he wanted me to play in the team. So I was happy to sign a new contract."
On his role, which is effectively as a defensive midfielder, though he helped set up one of Skacel's two goals in the 5-0 hammering of Aberdeen last weekend, Mrowiec added: "We all have different jobs to do.
"You have some players who score goals like Temps, Rudi and Kevin, but also some players who have jobs to do in defence."
According to team-mate David Obua, the job Mrowiec is doing for Hearts at the moment is similar to that of Rino Gattuso, the former Rangers player, at AC Milan.
"That's not bad because he's a good player but I play with Hearts, not in Italy," smiled Mrowiec regarding Obua's comparison.
"All I am doing is trying my best for the coach, the supporters and the team. And it is very nice when the gaffer and fans are happy with the job I am doing for the team.
"I can also help out in defence but midfield is my favourite position, having played there all the time in Poland.
Hearts headed into today's Tynecastle clash with Inverness Caledonian Thistle trailing second-placed Celtic by only three points. Mrowiec reckons the Gorgie club have already made people sit up and take notice but says forthcoming games against both Rangers and Celtic in Glasgow represent a real chance to show just how much Hearts are progressing.
"For me the team at the moment is stronger and we also have better players (than my previous seasons at the club]," he commented.
"We are having a very good time at the moment and we are trying to keep pressure on Celtic and Rangers.
"It is important that we win against the small teams like Aberdeen.
"Against Celtic and Rangers it is different, but we have shown everybody that we can win against Celtic and also play well against Rangers - we were unlucky in our game against them.
"I hope we can play in the Europa League next season, maybe even something bigger.
"We can challenge (the Old Firm]. Everyone feels the same and we are playing for this. (Celtic goalkeeper] Lukasz Zaluska is a friend and he says that Hearts are a very good team.
"In January I think we will be playing two games in Glasgow. These games will be our chance to show everybody what we can do."
With the likes of Lee Wallace and Andrew Driver close to being available again, Jefferies is going to have lots of options heading into the second half of the season.
And Mrowiec, for one, is determined to try and hang on to his starting place because he reckons competition for a place on the bench is going to become extremely hot.
"Next week Lee is going to be back and Driver, too. That is more positives for us and there is a big confidence in the team," he said.