Graeme McDowell believes Rory McIlroy's poor form this season is behind the world number two's decision to leave Horizon Sports Management to create his own management group.
McIlroy denied speculation at the Players Championship last week that he would create his own team with his father, close friends and associates, but McDowell confirmed the two-time major winner had decided on his second management change since October 2011.
The 24-year-old left International Sports Management just four months after winning his first major by eight shots in the US Open at Congressional, joining his good friend McDowell at Horizon.
"Management is a funny thing and when things are maybe not going 100 per cent on the golf course it is natural to question everything you are doing, from relationships, business and just everything you do," McDowell said after reaching the last 16 of the Volvo World Match Play Championship.
"Business-wise Rory's in the best shape he's ever been in his life" - Graeme McDowell
"Rory has made a decision about his management structure for whatever reason. I don't know the reasons because I haven't seen much of him the last few months as our schedules have been different.
"But it's just one of those things and you only have to look at the last 18 months and the job Horizon have done for Rory. He's had a phenomenal 18 months, signing the biggest deal in golf (with Nike) at the end of last year.
"Business-wise Rory's in the best shape he's ever been in his life and while he has struggled with his golf the early part of this season for whatever reason, I am sure the management company weren't giving him golf lessons or caddying for him. That's kind of his own deal.
"But when we are not on our game we have a tendency to, and I am not going to say make wrong decisions, but we do question everything in our lives, what we are doing and sometimes we have to make changes.
"Rory's decision is a fairly amicable break up and Rory just wants to do his own thing and surround himself with his family. That's fair enough.
"And as far as my relationship with Horizon Sports is concerned, they have done a phenomenal job for me the last five to six years, and it's pretty tough to look at Rory's scenario and say they've done a bad job.
"I've been through much the same situation as Rory before I signed with Horizon but when the stakes are high and the pressure is on, the old caddie and coaches are first to go. I guess management companies are not too far down that pecking order.
"It's disappointing to lose him as a management stablemate but we will go forward still very good friends."
The confirmation of McIlroy's multi-million pound deal with Nike coincided with a run of poor form at the start of 2013, which culminated in him walking off the course during the second round of the Honda Classic.
He initially told reporters he was in a "bad place mentally" before a statement was issued on his behalf citing pain from a wisdom tooth as the reason for his withdrawal.