The pair played together at Wednesday and were key figures in the club’s 2005 promotion-winning team.
Bullen and Heckingbottom - now in charge of Barnsley - started the the League One Play-Off Final where the Owls memorably beat 4-2 Hartlepool United at the Millennium Stadium.
“Paul always struck me as someone who was management material,” Bullen told The Star. “He’s got good knowledge of the game and always talked about things in a really good manner.
“He saw the game from a coacher’s eye.
“Paul Sturrock would quite often sit us down and have team meetings and ask for opinions and Paul was always one of them who was quite comfortable giving his views and saying the way he felt in certain circumstances.
“You had a sense that he would make a good coach if given the right opportunity.”
Heckingbottom has done a superb job at his hometown club Barnsley, leading the South Yorkshire club to two Wembley wins in the space of two months in 2016.
The 39-year-old steered the Reds to Johnstone’s Paint Trophy and League One Play-Off Final glory last season, culminating in him becoming the Barnsley on a full-time basis.
Ex-Wednesday captain Bullen said: “Paul has done a fabulous job. He took over in difficult circumstances when Lee Johnson got head-hunted and left for Bristol City.
“Paul learned his trade in the youth-team and was also helping out at first-team level. It helped Paul that he already knew the players. It would probably have been a steady transition for him.
“He has been given his opportunity and, frankly, what he did last season was pretty unbelievable.”
Following back-to-back victories over Birmingham City and Norwich City, Heckingbottom’s Reds side are currently 11th in the table, just three points adrift of the Owls.
“Paul is very, very calm in the way he handles things and even when you listen to his interviews at the moment, he doesn’t get too down or disappointed if they’ve had a defeat and he doesn’t get too high or carried away if they’ve had a good result,” said Bullen.
“Their last two results against Birmingham and Norwich have been phenomenal.
“Barnsley have taken a whole different philosophy as a football club in regards to recruitment. They look to recruit young, hungry players who want to prove themselves.
“Barnsley have a lot of energy in the team and have worked their way up the table.
“Some of the results they’ve had this season have been truly outstanding. To go to Birmingham and win 3-0 was absolutely fantastic. They also put four past Wolves so some of their best performances this season have been away from home.”
He added: “Supporters will have given Paul that little bit of leeway because he is Barnsley born- and-bred and he has played for the club but sometimes that is added pressure. You feel that yourself and you take on that burden but Paul has done fantastic.
“Full credit to him, his staff and players for getting promoted and then producing some of the results they have done this season in what I believe is the hardest Championship ever.”
Bullen and Heckingbottom have stayed in touch and still regularly speak to each other but the duo will be in opposite dug-outs tonight when Wednesday entertain the Reds. And Bullen hopes the Owls can ruin his old pal’s return to Hillsborough.
“I don’t speak to Paul every week but I might speak to him once a month or drop him a text every now and then to see how he’s doing,” said Wednesday coach Bullen. “We’ve got a good relationship and I have a lot of respect for him.
“But for 90 minutes, friendship goes out of the window and it will be the same for Paul. He will be wanting to beat us and we want to beat them to get three points for our team.”
Bullen believes the Owls can ill-afford to take their South Yorkshire counterparts lightly as they bid to bounce back following Saturday’s reversal at Reading.
“I have watched Barnsley live a couple of times so we know how tough it is going to be,” said the Scot. “Barnsley are a hard team to break down.
“It will be a good derby game.
“I’m sure Barnsley and their supporters have probably pencilled this in as a game that they are looking forward to. They will bring a big, big following and will want to put one over us. One hundred per cent. They will see that we are a big scalp, especially after the season we had last year.
“I’m sure they will be excited about coming to Hillsborough and there will be no fear for Barnsley.”