ORCHARD PARK, N.Y. -- Whether it was sitting together in a golf cart watching training camp or sharing dinner and drinks at a nearby restaurant, Bills owner Terry Pegula and general manager Doug Whaley were nearly inseparable last summer.

Some nine months later, their professional relationship soured to such an extent that Pegula fired Whaley and his entire scouting staff on Sunday.

The decision was reached shortly after the two met at 8 a.m., a day following the NFL draft, and it completed a front-office purge that began with coach Rex Ryan being fired in the final week of last season.

Pegula's voice cracked briefly with emotion when discussing the latest move, saying: "There were a few tears around the building, to be honest with you. He's a good guy."

But not good enough to keep his job, with Pegula saying he reached the conclusion following a lengthy off-season review.

It's a shake-up that further solidifies the influence rookie coach Sean McDermott has gained in the three months since being hired. The 42-year-old detail-oriented defensive specialist has become the voice of the franchise in discussing all team-related topics, including free agency and the draft.

Pegula said the timing coincided with the end of the draft, but he declined to detail the reasons why the overhaul was necessary. Nor would Pegula explain his reasoning for showing Whaley the door while praising the collaborative approach that took place between the GM and McDermott in the draft room.

"We have certain aspects we need to get a little better in," Pegula said. "(Whaley's) a smart man, but we made the decision. And the reasons remain private to us."

Pegula said "things change," when asked why he signed Whaley to a four-year contract extension in January 2016, and then backed him this January after Ryan was fired.

Pegula also took the emphasis off McDermott's authority by saying the decision to fire Whaley was made by him and his wife, Kim.

The Bills also dismissed player-personnel director Jim Monos and Kelvin Fisher, the team's former amateur scouting director who had previously been demoted to an advisory role.

Pegula will immediately begin a GM search and said it was too early to speculate on candidates. He said McDermott would have some input.

One possible candidate is Carolina Panthers assistant GM Brandon Beane because of his ties to McDermott, who spent the previous six seasons as the team's defensive co-ordinator.

McDermott on Saturday praised Whaley's role in the draft process but sidestepped questions regarding the GM's job security.

The Bills made six picks and swung several trades in addressing immediate and long-term needs.

Buffalo opened by acquiring two selections, including a first-rounder next year, in a trade with Kansas City to move back 17 spots and select LSU cornerback Tre'Davious White at 27th.

The Bills have now gone through six general managers during their 17-year playoff drought -- the longest active streak in North America's four major professional sports. It's the first GM search for the Pegulas, who retained Whaley when they purchased the team in October 2014.

Whaley worked up the scouting ranks with the Pittsburgh Steelers, before the Bills hired him as an assistant general manager in 2010. He was groomed to become the GM and took over the job in May 2013 when Buddy Nix stepped down.

The Bills' drafting history had been spotty this decade.

Of the 35 players Buffalo drafted from 2010-13, only defensive tackle Marcell Dareus and left tackle Cordy Glenn remain on the roster.

Whaley has been second-guessed on a number of selections, including the decision to trade two draft picks -- including Buffalo's 2015 first-round selection -- to Cleveland to move up five spots and pick receiver Sammy Watkins with the fourth selection in the 2014 draft.

It was considered a high price to pay in a draft that produced a bounty of top-flight receivers.

Whaley acknowledged he took a gamble and suggested his tenure in Buffalo might well be judged on that one move.

Both of Pegula's Buffalo-based sports franchises are hitting the reset button. Pegula fired Sabers GM Tim Murray and coach Dan Bylsma 10 days after the NHL season ended two weeks ago.

Without going into detail, Pegula said he is close to hiring a general manager.

Between the two teams, the Pegulas have now employed a combined seven coaches and three GMs since purchasing the Sabres in February 2011.

Pegula chalked up the rate of change as being common in sports, and disputed the notion it reflects poorly on him.

"We're going to try to make the best decision we can in the future," Pegula said. "We've made big decisions all our lives."