The Arizona Diamondbacks acquired All-Star pitcher Dan Haren from Oakland and traded major league saves leader Jose Valverde to Houston in separate swaps involving 12 players Friday.

Oakland also sent right-hander Connor Robertson to Arizona and received six players: left-handers Brett Anderson, Dana Eveland and Greg Smith; infielder Chris Carter; and outfielders Aaron Cunningham and Carlos Gonzalez.

The NL West champion Diamondbacks got reliever Chad Qualls, infielder Chris Burke and right-hander Juan Gutierrez from the Astros.

Haren, who was 15-9 with a 3.07 ERA this year, became the first elite starter to switch teams this offseason -- which could set off a flurry of moves by other teams in search of pitching.

The Minnesota Twins are listening to trade offers for two-time Cy Young Award winner Johan Santana, who can become a free agent after next season. Baltimore is thought to be shopping lefty Erik Bedard.

Haren joins a Diamondbacks rotation that includes 2006 NL Cy Young Award winner Brandon Webb. Arizona also hopes to get Randy Johnson back from injury next year.

"We had a significant amount of interest in Dan, as you would expect," Athletics general manager Billy Beane said. "As I said from the start of this winter, the way we went forward was going to be, first and foremost, on the health of the club, and how much interest there was in a guy like Dan and what was going to be the return if we did decide to trade him."

With new general manager Ed Wade, the Astros have been one of baseball's busiest teams this fall. They traded five players to Baltimore on Wednesday for star shortstop Miguel Tejada, 10 days after signing free-agent second baseman Kaz Matsui to a $16.5 million, three-year contract.

Valverde, who had 47 saves in 54 chances this year, takes over as Houston's closer from inconsistent Brad Lidge, a 2005 All-Star who was traded to Philadelphia on Nov. 7 in a five-player deal that sent speedy outfielder Michael Bourn to the Astros.

Haren quickly emerged as the ace of the A's staff this season following the departure of Barry Zito to the San Francisco Giants. The right-hander set career bests for wins, strikeouts (192) and ERA. His ERA was the third-lowest in the American League. In 2004, the A's obtained Haren from the St. Louis Cardinlas in trade for Mark Mulder.