The Frenchman admitted change was part of McLaren's perpetual movement and its endless quest to seek improvement.
"I think you have to realise that Formula 1 is all about change," Boullier said in an interview on McLaren.com
"Change is what drives our sport – change in drivers, in regulations, in races, in almost everything. And we’ll change again and again and again as we continue to improve our fortunes both on and off the track.
"Dave was offered an opportunity with another team, and we didn’t want to stand in his way. We’ve been discussing this together for some time; it’s not a sudden decision, and we’re happy for him."
Former chief mechanic Paul James takes over Redding's role while Andrea Stella will see his current race engineering task expanded to include handling the team's sporting relationship with the FIA.
"As McLaren’s chief mechanic, Paul is the best in Formula 1 – and that’s not merely my opinion, but that of many of my peers at McLaren who’ve had the opportunity to work up and down the pit-lane in many other teams, as I have of course.
"I think what makes Paul unique is his unflinching honesty. He’s demanding of his team, but equally demanding of himself, which makes him both popular and inspirational.
"He’s able to dive straight to the heart of any problem – and quickly and effectively find a solution – and it’s that quality that I’m sure will serve him very well in this new role.
"Andrea will become our chief point of contact for any interaction we have with the FIA during a race weekend, liaising with Charlie [Whiting] and his team of scrutineers and stewards to ensure compliance and fair play.
"Andrea is a clever, perceptive man, with a fearsome intellect and a really broad focus. I’d describe him as a very precise thinker."
Finally, Kari Lammenranta, who officiated as Fernando Alonso's number-one mechanic, is promoted to chief mechanic, while Marc Cox will take over responsibilities on the Spaniard's car.
"Kari is a no-nonsense guy," insists Boullier.
"He’s a tireless and diligent worker, he never complains, and he really understands what it takes to make a racing car work.
"Coxy has another nickname, "One Man Army', which I think tells you all you need to know about just how effective he is at his job."
With all changes coming from within, it's a reflection on McLaren's inner strength as Boullier underlines.
"That not only tells you a lot about the strength in depth at McLaren, but it also indicates the very high esteem in which we regard our own people," he adds.