The moves come with the D-backs mired in last place in the National League West for the second straight season with a 31-48 record. Arizona named Jerry Dipoto interim general manager and Kirk Gibson interim manager for the remainder of the season.
"I appreciate the commitment and dedication that Josh and A.J. demonstrated during their tenures," managing general partner Ken Kendrick said. "Their dismissal is a significant decision, but one that we find necessary in order to achieve a direction of winning consistently on the field again. We have a number of talented players, but obviously see great room for improvement. We look forward to bringing permanence to these two baseball leadership roles."
Byrnes was named to his post in November 2006 after serving as assistant GM of the Red Sox, while Hinch took over for Bob Melvin on May 8, 2009, and compiled an 89-123 mark at the helm.
After finishing 76-86 in Byrnes' first season as GM in 2006, the D-backs jumped to 90 wins and reached the 2007 NL Championship Series, where they were swept by the Rockies. The following season, the D-backs started off 20-8, but wound up finishing with an 82-80 record, and Byrnes' relationship with Melvin soured.
Following a 12-17 start to the 2009 season, Byrnes dismissed Melvin and hired Hinch on May 8. The move immediately sparked controversy given the fact that Hinch, who was the team's farm director, had never managed or coached at any level.
It was thought at the time that Hinch's familiarity with the young players, most of whom had come up through the Minor League system, would be a big plus for him. Also, at the press conference to announce the hiring, Byrnes referred to Hinch's knowledge of "organizational advocacy" as something that helped trump his lack of experience.
"He's never done a double-switch before," Byrnes said at the time. "He knows what it looks like. He'll figure it out. He brings unique leadership and perspective to the job. We're not here to reinvent the wheel. But to change the nature of the job, a little bit? OK, we'll do that.
"They might not feel A.J.'s experience yet, but they're going to feel his advocacy."
The move was not received well by some in the D-backs clubhouse, and the team limped to a 58-75 finish.
There were high hopes for the D-backs this spring following an offseason in which Byrnes added relievers Bobby Howry and Aaron Heilman along with second baseman Kelly Johnson and first baseman Adam LaRoche. In addition, Hinch had spent the offseason developing a better rapport with the players.
"There is zero room in this clubhouse, in this spring for the negativity and pessimism that existed before," Hinch said on the day of the club's first full-squad workout. "And any of that stuff that happened last summer doesn't affect how our performance is going to be moving forward. It really is about where we're headed, where we're going, what we're going to do to prepare ourselves for a successful season."
Success, though, was not forthcoming.
After playing nearly .500 baseball for much of April, the D-backs went 0-6 on a homestand in early May and later in the month had an 0-9 road trip and a 10-game losing streak overall.
That prompted the team's ownership to undertake an evaluation of the organization.
"We're to the point where this team hasn't won," team president and CEO Derrick Hall said in early June. "They collectively don't win. There's something that's missing and it's our responsibility now to assess the entire organization, to identify the problems and correct those problems as quickly as we can. From top to bottom, we're going to uncover every rock."
That process apparently led to Thursday's moves.
"These decisions come as a first and major step in our thorough evaluation of our team," Hall said in a statement announcing the moves. "We have all been disappointed in the results over the last few years, and we have come to the conclusion that a change in the leadership of our baseball operations staff is necessary at this time. This franchise has enjoyed tremendous success over the years and we want to get back to our winning ways. The loyal staff of this organization, as well as all of our fans, hopes for and deserves better results on the field."
Byrnes was in the third year of an eight-year extension he signed in the spring of 2008, while Hinch has two years left, following this season, on his contract.
FOXSports.com reported that the D-backs are on the hook to the pair for more than $7 million.
Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.