The stunning events that led to receiver Wes Welker signing with the Denver Broncos on Wednesday, and the New England Patriots filling the void with Danny Amendola, came down quickly behind the scenes, according to sources familiar with the negotiations.

The breaking point came Tuesday in the mid-afternoon before the official start of free agency, when the Patriots and Welker's representatives halted contract talks. The team's offer, a two-year, $10 million pact with incentives that could have pushed it as high as $16 million but in the eyes of Welker would be extremely difficult to reach, wasn't accepted.

At that point, Welker and his representatives intensified their pursuit of other offers, and it helped that some groundwork had previously been laid with the Broncos. Likewise, the Patriots turned their attention to Amendola, who was their top choice if things didn't work out with Welker (and in the eyes of some on the other side of the negotiating table their top choice all along).

A year after being $1 million apart on a three-year deal with the Patriots, Wes Welker agreed to a two-year, $12 million contract with the Denver Broncos. AP Photo/Matt Slocum

Things came together quickly with the Patriots and Amendola on a five-year, $31 million deal with $10 million guaranteed, and at that point, there was no looking back for the team. While the Patriots would have been pleased if Welker accepted their proposal -- owner Robert Kraft said Monday that he hoped Welker would retire as a Patriot -- the possibility of losing him and Amendola was deemed too risky, so they moved close to locking in the deal with Amendola not long after free agency began Tuesday.

After almost a year of on-and-off talks, had the Patriots felt they were closer to a possible agreement with Welker, perhaps they wouldn't have pushed so hard for Amendola at that point. But it was a stalemate that the club felt showed no signs of resolving itself -- the Patriots ready to move on, and Welker slowly but not completely becoming more comfortable envisioning himself catching passes from Peyton Manning instead of Tom Brady.

This is how it often works in free agency, with timing of the essence. Patriots coach Bill Belichick regularly says that he makes decisions in the best interests of the team, and in the 27-year-old Amendola he saw a quick, sure-handed target who was five years younger than Welker and committing to a lengthy five-year term. If it couldn't be assured that Welker would be back at a contract the team was comfortable with, the Patriots were willing to move on at that point with a player whom offensive coordinator Josh McDaniels had worked with in St. Louis in 2011.

Yet even after Welker received a two-year, $12 million offer from the Broncos on Wednesday, a call was made to the Patriots to see if the club would sweeten its offer. The Patriots did not have an immediate response, which led some in Welker's camp to believe a better offer was a possibility in part to keep him away from the Broncos, one of their top competitors in the AFC. Ultimately, the club informed Welker and his representatives that they had entered into another commitment, which Welker's camp assumed all along was Amendola.

So Welker called the Broncos -- who, according to a source, were initially concerned about insulting Welker with their offer because they already had made other financial commitments -- and told them he was on board. While not the offer he was hoping for at the start of free agency, it was easier for Welker to accept it from a team other than one that he'd produced at such a high level for over the past six seasons, the source said.

The initial response that Welker received from Manning, executive vice president of football operations John Elway and others in the organization has been "a great feeling" and given him greater comfort in making the move.