Hours later, the team announced it had signed Punto to a two-year contract. He replaces Lowrie -- both are switch-hitters who can play all over the infield.
The 34-year-old Punto gets a $3 million, two-year deal. Rangy and reliable on defense, he batted .278 with one homer and 20 RBIs in 63 games with the World Series champion St. Louis Cardinals last season. He had a .388 on-base percentage.
Melancon gives the Red Sox a potential replacement for Papelbon, who signed a $50,000,058, four-year contract with the Philadelphia Phillies. Melancon had 20 saves for Houston this year, going 8-4 with a 2.78 ERA in 71 relief outings during his first full major league season.
Red Sox general manager Ben Cherington wouldn't commit to the notion that Melancon would be the club's next closer, but the GM said the right-hander is capable of filling that role.
"We believe he's definitely capable of closing and capable of pitching in the ninth inning for us," Cherington said Thursday morning. "But those are questions for Bobby [Valentine], with help from his pitching coach, during spring training to answer and figure out the right roles for everyone."
The 26-year-old right-hander pitched a total of 35 games in 2009 and 2010 with the New York Yankees and Houston.
"The more experience he was able to get gave him more confidence to go out and throw," Astros manager Brad Mills said on a conference call.
Mills wasn't ready to name his new closer.
"We'll have to assess the situation," he said. "We're not going to figure out our entire pitching situation on Dec. 14."
Weiland will be given a chance to win a spot in the Houston rotation. To make room on their 40-man roster, the Astros designated infielder Brian Bixler for assignment.
Lowrie spent time on the disabled list each of the last three seasons because of problems with his left wrist, left forearm and right shoulder, and a bout with mononucleosis. He played all four infield positions last season and hit .252 with six homers and 36 RBIs in a career-high 88 games.
"For me it's about playing, and that's always what I've wanted," Lowrie said. "Hopefully, I get that opportunity in Houston."
But he is going from a perennial contender to a rebuilding team.
"I had a couple of years of playoff experience in Boston and I think it was an opportunity for me to learn what it is on the biggest stage in baseball," Lowrie said. "I want to bring that experience and that winning attitude and culture to Houston. Even if the team is rebuilding, it's about winning."
Weiland, 25, was 0-3 with a 7.66 ERA in seven games, including five starts, this year for Boston. He spent most of the season in the minors but was promoted when several Red Sox starters were sidelined by injuries.
Mills said Weiland would compete for a spot in Houston's rotation.
The diminutive Punto made 10 postseason starts at second base for the Cardinals. He is a .249 career hitter with 14 home runs and 218 RBIs in 887 career games with the Phillies (2001-03), Twins (2004-10) and Cardinals (2011). His teams have made it to the postseason four times.
Punto's salary is $1.5 million each of the next two years. He can make an additional $250,000 each season in bonuses for days on the active roster.