The trade didn't come as a surprise to Castilla, who had heard rumblings in September that he could be dealt to make room for Zimmerman.
"They wanted to open up room for Ryan, and that's good," said Castilla. "The trade will work out for me, too. I'll be in San Diego and with a team that made the playoffs this year. Ryan Zimmerman is a great player and great prospect."
Castilla, 38, signed with the Nationals as a free agent before the 2005 season and hit .253 with 12 home runs and 66 RBIs, a far cry from the 35 home runs and 131 RBIs that he put up for the Rockies in 2004.
Castilla, along with other players, including Jose Guillen, sometimes complained that his power numbers were down because he played in the spacious RFK Stadium, sentiments that did not sit well with upper management.
He also played most of the season with an injured left knee, which he hurt during an exhibition game against the Mets last March. He ended up missing the final two weeks of the season because of the injury, and that gave Zimmerman the chance to play every day. Castilla said that his knee is now 100 percent healthy.
"Obviously, we expected more after we signed Vinny, but I think that had to do with his health," said Bowden. "I thought we were expecting a 20-home run, 80-RBI guy. He certainly fell a little short of that."
Zimmerman ended up proving why he was the fourth overall pick in the 2005 First-Year Player Draft. In 20 games, he hit .397 (23-for-58) with six RBIs. He also played sparkling defense at third base, which had Bowden comparing him with Brooks Robinson, Scott Rolen and Mike Schmidt.
"I told you when I drafted him that he was that type of player. Obviously, we are trying to build this thing from the bottom up," said Bowden. "We signed Vinny until we were able to get a young player to play [third base], and it's going to happen a year before [we thought] it would. We are very pleased with Ryan's development."
Zimmerman, who is playing in the Arizona Fall League, feels that his success this past September will carry over into the 2006 season.
"I'm very lucky to sign with a great organization," said the 21-year-old Zimmerman. "There will be some rough times [in the future], but I expect to do well."
According to Bowden, the trade also means that Brendan Harris, considered a long shot just days ago, will get a serious look to make the team out of Spring Training as a backup infielder.
Harris played for Triple-A New Orleans this past season and hit .270, with 13 home runs and 81 RBIs. He currently is hitting .397 in the Arizona Fall League.
"If Zimmerman wasn't ready, we certainly would have had Brendan Harris over there," said Bowden.
Lawrence, who will be a fourth or fifth starter in the Nationals' rotation, had his worst big-league season in 2005, going 7-15 with a 4.83 ERA. During the postseason, he was sent to the bullpen, and he didn't give up a run in 2 1/3 innings against the Cardinals in the National League Division Series.
"I had a little bad luck," said Lawrence. "I had a horrible September. I thought I pitched well until the middle of August."
But the Nationals feel that his performance will improve, as he will be pitching in RFK Stadium, which is larger than the Padres' PETCO Park.
"[RFK is] definitely a big, spacious park," said Lawrence. "You really have to hit it to get the ball out of there. I really work on movement [and] changing speeds, so having the humidity really helps me. Obviously, having a ballpark that size and a good defense, I'll benefit from that. I'm expecting good things. I'm not going to have the season that I had last year."
Lawrence, 29, won 49 games for San Diego from 2002 to 2005, including a career-high 15 in 2004. During that same span, he not only posted more wins than any other Padre, he averaged 34 starts and 205 innings per season.
"It's important that we get innings," said Bowden. "We said that last [January] when we signed [Esteban] Loaiza. It's important to get a guy that is capable of pitching 200 innings. It's a very valuable thing.
"He doesn't throw that hard. He throws 84 to 86 [miles per hour], but he knows how to pitch. He throws strikes and he goes after the hitters. If he had overpowering stuff, he would be a No. 1 or a No. 2 pitcher instead of a four or a five."
Lawrence said that the Padres have a surplus of starting pitching, so he wasn't surprised to be dealt to the Nationals.
"I think both sides benefited," he said. "I'm excited to come to a new city and do the thing that I love to do, and that's pitch. I feel that I have a lot of good years in front of me."
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.