Shortly after announcing they had released Young, the Bills followed up to confirm reports that they had acquired Tarvaris Jackson in a trade with the Seattle Seahawks in exchange for an undisclosed draft pick.
It was a surprising turn of events that came in the final week of the preseason, and after Young struggled in his bid to win the backup job in a 38-7 loss to Pittsburgh on Saturday.
Young posted comments on his Twitter account indicating his time in Buffalo was over on Monday morning.
That was after the Bills reached an agreement with Jackson to restructure the final year of his contract and complete the trade Buffalo and Seattle had agreed to Sunday night.
"Respect Bills fans," Young wrote. "I want to thank the Bills organization for the opportunity and with the organization and my teammates good luck this season."
Jackson traveled overnight to Buffalo, and was expected to join his new teammates for practice Monday afternoon.
The trade wasn't completed until the Bills (No. 19 in the AP Pro32) reached a deal with Jackson's agent, Joel Segal, to restructure the final year of the player's contract, according to a person familiar with discussions. The person spoke on the condition of anonymity because the Bills do not discuss contract talks.
Jackson was scheduled to make $4 million this season, a figure the Bills deemed to be too expensive for a backup player.
The Bills (0-3) are preparing to complete their preseason schedule at Detroit on Thursday, when Jackson will have an opportunity to play.
Jackson is a seven-year veteran who has gone 17-17 as a starter with Minnesota and Seattle. He had a 7-7 record with the Seahawks last season, but his future was left uncertain after Seattle acquired Matt Flynn in free agency this offseason, and after using a third-round pick to draft Russell Wilson in April.
The Bills quickly ran out of patience with Young, who had signed a one-year contract in May to compete with returning backup Tyler Thigpen for the No. 2 job behind starter Ryan Fitzpatrick.
Young had the edge to win the backup job before he struggled on Saturday. He threw two interceptions, the first coming on his first pass attempt, and finished 12 of 26 for 103 yards passing in playing the entire second half.
It was a sudden turn of events for Young, who last week had earned a thumbs-up from quarterbacks coach David Lee.
"I'm really pleased with how much he studied and how he has slowly gotten better and better," Lee had said. "Is he ready for the season? Not yet, but he's getting better every day."
And coach Chan Gailey has maintained there's only room for one backup, because the No. 3 job is going to receiver/wildcat specialist Brad Smith.
It is the latest blow to Young's once-promising career. After leading Texas to the national championship in 2006, Young was selected third overall in the draft by the Tennessee Titans and was the NFL Offensive Rookie of the Year.
The Titans eventually ran out of patience with Young and released him last summer. Young had a disappointing season as Michael Vick's backup in Philadelphia last year.
Jackson has had an up-and-down career since being selected by Minnesota in the second round of the 2006 draft. He spent five years with the Vikings, including a 2007 when he went 8-4 before losing his starting job.
Jackson signed a two-year contract with the Seahawks last year, and was credited for playing a major role in the team's turnaround after a 2-6 start. He had career numbers in completions (271), attempts (450), 3,091 yards passing with 14 touchdowns and 13 interceptions.