But Gonzalez said he understood what was going on in Oakland.
"And I spoke to Billy," he said. "I understood the matter. I was all ears for Billy and I thanked him for everything he did for me. I appreciated it."
It marked the fourth time in his career that Gonzalez had been traded. He had Minor League stints with the White Sox and Phillies. During the first three trades, Gonzalez was a throw-in, but he feels honored that he was a major player who is going to the Nationals.
"It's unbelievable. It's a unique thing. It's different. It's cool. It's exciting. It's something different," Gonzalez said. "All in all, this is baseball. When it's all said and done, this is what people pay to watch. This is fun. This is what keeps the game going -- the excitement, the trades, the changes. It's bittersweet, but at the same time -- in the end -- it will pan out to what everybody wants."
Getting Gonzalez was a top priority for the Nats after they were unable to reel in left-hander Mark Buehrle, who signed with the Marlins.
Gonzalez joins a rotation that will include Stephen Strasburg, Jordan Zimmermann, John Lannan, Chien-Ming Wang and Ross Detwiler.
"I love everything about it," Gonzalez said. "I remember growing up watching Chien-Ming Wang with Yankees. You are talking about great guys in that rotation. I don't want to step on anybody's toes. I want to be a part of it as much as possible.
"Hopefully, when I break into camp with these guys, it's going to be fun. Our hard work from the offseason is going to pay off during the regular season."
Last season, Gonzalez was 16-12 with a 3.12 ERA and had 197 strikeouts in 202 innings. He will not be a free agent until after the 2016 season.
"I feel great. It's a positive thing the Nationals pulled trigger and they gave me the opportunity to go to the National League and try to compete for a playoff spot and a World Series," Gonzalez said. "After talking to [general manager] Mike Rizzo and the way he sounds, I think this is perfect. He sounds like a guy who is putting the pieces together. He wants to compete and win a title. Those are the people you want to play for."
"Billy Beane was great with what he did for me, sending me to Washington. He thought it was a great idea. He knew how important it was for them over there. I appreciate what Billy did and what the Nationals have done for me now."