The Los Angeles Dodgers, Boston Red Sox and New York Yankees were rumored to be pursuing Hudson, but the Braves swooped in and got the Oakland ace for outfielder Charles Thomas and pitchers Juan Cruz and Dan Meyer.
"Honestly, it was tough to hear the news," Hudson said in a phone interview. "I understand Billy has to do what he feels is best for the organization. You've got to move on sometimes. The hard part for us is all the friendships we've built in the Bay Area."
Hudson's now-former teammate Mulder agreed with those sentiments in an interview with ESPN Radio.
"The two of us had lockers next to each other for the last 4½ years," Mulder said. "You kind of figure something like this is going to happen, but it's not as much about losing a guy on your team, it's about losing one of your best friends."
"This winter, we have set our sights on going back to sort of the old-fashioned Braves way of building championship teams with dominant pitching," Atlanta general manager John Schuerholz said. "That's what we think we have done, and we are excited about the pitching staff we have put together for the season."
The Braves began the day by reaching agreement with Smoltz on a $20 million, two-year contract.
Schuerholz said the flurry of activity "helps us create one of the stronger pitching staffs we've had here for many, many years."
He first began talks with Beane during last weekend's winter meetings in Anaheim.
The trade was finalized around midday Thursday, said Beane, who until Wednesday was still talking to three teams about Hudson. The A's wanted to make sure they acquired a pitcher -- Meyer -- who could compete right away for a spot in the rotation.
"Meyer has pitched at every level successfully," Beane said. "He has a sterling track record up to this point, and he's a guy we've always liked."
Mulder said that, despite what the A's are getting in return, they're going to miss Hudson.
"You're getting one of the best guys in baseball, not only on the field and off the field, but just the competitor that he is," he told ESPN Radio. "You're getting a leader. You're getting a guy who wants the ball and who's going to go out and get the job done. When Huddy doesn't have his best stuff, he is out there competing and just flat-out getting it done. That's what we are going to miss."
The Georgia-born Hudson, who rooted for the Braves as a kid, posted 81 wins from 2000-04, tied for most in the AL over that span. He is 92-39 with a 3.30 ERA lifetime.
"I always wondered how it would be to put on a Braves uniform and play in Atlanta," Hudson said. "Now I get to see. Hopefully I'll do what all the Braves pitchers had done."
The 29-year-old righty said if he had to leave Oakland, joining a successful franchise like the Braves, who have won 13 straight division titles, makes the move a little bit easier.
Beane said he "needed to do something bold," but it still wasn't an easy decision.
"This was the most difficult phone call I've ever had with a player about a trade or a departure," Beane said. "I spent a lot of time on the phone with him. It was very difficult. We're going to miss him, there's no question. I don't think the expectation is that we'll be able to replace his personality and exactly what he brought to this franchise the last five years."
Hudson was 12-6 with a 3.53 ERA in 27 starts this season. He made the All-Star team for the second time but did not pitch because of a strained left side that put him on the disabled list for a month.
Earlier this month, Hudson set a March 1 deadline for the A's to offer him a contract extension, or he planned to leave as a free agent following the 2005 season -- following the likes of MVPs Jason Giambi and Miguel Tejada. Hudson didn't want the distraction of contract talk during spring training.
Rather than lose another homegrown superstar for nothing, Beane decided to land three valuable prospects even at the cost of a cornerstone of the small-market franchise's unlikely success over the last half-decade.
Beane is happy to see Hudson heading for the NL, though swapping him out of the league wasn't a priority.
"We certainly traded a major part of our franchise in Tim, but we've also upgraded," Beane said. "I wasn't eager to play against him. Quite frankly, no one in the division called. It wasn't an option. I told Tim usually it's not something you worry about, but I'm not disappointed he's about as far away professionally as he can be."
Mulder said Oakland's constant retooling is tough on the team.
"What's kind of tough is you see us lose these guys, but then you see Anaheim go get Vladimir Guerrero, Seattle getting (Richie) Sexson and (Adrian) Beltre, Anaheim getting (Bartolo) Colon. That's the tougher thing -- seeing the other teams in our division going out and getting better, and us still trying to compete, losing guys," he said.
Thomas made his major-league debut last season and batted .288 with seven homers and 31 RBI. Cruz was 6-2 with a 2.75 ERA in 50 relief outings. Meyer was 0-0 in two games with Braves after going 9-6 with a 2.49 ERA at Double-A Greenville and Triple-A Richmond.
Vasquez, 26, also made his major-league debut last season, pitching in two games for Kansas City. He spent most of the year at Triple-A Wichita, going 4-5 with a 4.68 ERA and 18 saves.
Information from The Associated Press was used in this report.