The decision and timing to remove director of rugby Diamond was questioned as the former Sale Sharks and Worcester Warriors boss left Kingston Park after just one game in the Prem this season.
Diamond had led the club through challenging times from when he arrived in January 2024 with them struggling financially and unable to compete with the other top-flight clubs.
With the Red Bull takeover completed just a few weeks before the new season began, he was forced to conduct a rapid global recruitment plan to build up the squad.
In his place, Alan Dickens was promoted to head coach, but the Red Bulls are still to win a game in the Prem this season.
Petrie says it is part of the club wanting to change strategy.
“In coming in, you look at what you feel you need from a coaching structure going forward,” he said.
“While we’re very appreciative of what Steve did, we felt that we needed to move in a different direction.
“We felt strongly that was the right thing to do and put in place a coaching structure that can help take us forward.
“That was always going to take a bit of time to bed in at this point of the season but it’s been really good for us over the last few weeks to further augment that with bringing in a guy like Stephen Jones as attack coach.
“I appreciate that results have been tricky but it’s been really encouraging to see how the team has started to bond and grow together.
“We’ll continue to see that improve with the players and coaches we’ve brought in and we’ll look forward to that developing this season and into next season as well.”
