Castillo's arrival stabilizes the No. 2 spot in New York's lineup, which has seen 14 different players bat after leadoff hitter Jose Reyes this year. The 31-year-old Castillo also gives the Mets another switch-hitter in the top half of the lineup to go along with Reyes and Carlos Beltran, when the center fielder returns from a strained oblique muscle.
"It's a nice addition for us," Mets manager Willie Randolph said. "I've always admired his game. He's a tremendous player and brings a lot to the table, especially defensively, for us."
Castillo formed one-half of a potent top-of-the-lineup punch, along with current Dodgers outfielder Juan Pierre, that helped propel the Marlins to the World Series title in 2003.
Castillo now gets an even more dangerous threat batting ahead of him in Reyes. The speedy shortstop entered Tuesday's game batting .302 with seven homers and 10 triples. Reyes is on pace to swipe 75 bases and score 115 runs, compared to Pierre's line of 65 steals and 100 runs scored in 2003.
Lo Duca, a teammate of Castillo's in Florida for a season and a half, called the second baseman one of the favorite teammates he has had.
"He's a gamer," LoDuca said. "He gets on base. He's a great defender. He does a lot of little things."
Castillo hasn't been as active on the basepaths since he injured his hip in 2002. He finished that year with 48 steals, but he hasn't topped 25 steals since. But the 31-year-old said he looked forward to playing his home games on Shea Stadium's grass surface, as opposed to the less forgiving artificial surface at the Metrodome.
In addition, Castillo owns a .293 career average at Shea Stadium to go along with a home run, three triples and 17 RBIs in the 61 games he has played in the ballpark.
"I've played a lot of games over there," Castillo said. "I know Shea Stadium. I like this stadium and the fans."
Castillo, who spent the first 10 years of his 12-year career with the Marlins, also said he will enjoy returning to the National League brand of baseball.
"All my career, I've played more ballgames in the National League, so I feel like I'm coming back home," Castillo said. "I know the game here, and that's good for me."
Castillo's arrival will cut down on the playing time for Ruben Gotay, who has gotten the majority of the starts at second base in the past month filling in for the injured Jose Valentin. But Gotay didn't show any resentment toward the new second baseman.
"They're the front office -- they know what they're doing," Gotay said. "They're bringing somebody who knows how to play second base. I'm going to keep learning from him and playing hard and see what happens."
Randolph said Gotay technically wasn't the starting second baseman, since he was splitting time with Damion Easley and Marlon Anderson at the position and would have continued to do so as the season progressed.
But Randolph nevertheless made sure to speak to Gotay to keep his spirits up.
"I talk to my players constantly -- that's why, I think, they do a good job," Randolph said. "All my backup players, they feel like they're a part of what we're doing here. Just because we bring in another player doesn't change the way you feel about yourselves."
Having filled their hole at second base for now, the Mets nevertheless will face some decisions at the position at the end of the year, with Valentin, Castillo and Gotay all eligible for free agency after this season.
General manager Omar Minaya said Monday that the Mets would have given Castillo serious consideration in the offseason for their impending vacancy at second base, so the acquisition now gives the team a first-hand look at the goods.
As for Castillo, he isn't worrying right now about what lies ahead for him in the offseason.
"We've got two more months left and I'll try to help this team -- this is a good team -- go to the World Series," Castillo said. "That's what I want to do. We'll see what happens."