Haren, a Monterey Park, Calif., native, could have a large cheering section in the stands for his Angels debut. His family and friends and the chance to play for a contending club made the opportunity to go home again even more exciting for Haren.
"Being able to be near family and going to a ballclub that is dedicated to winning -- for not just this year but a lot of years -- I am very excited for the chance to go there and win," Haren said on Sunday.
The right-hander was acquired from the D-backs on Sunday evening for left-handers Joe Saunders, two prospects -- right-hander Rafael Rodriguez and lefty Patrick Corbin -- and a player to be named later.
Following Haren, the Halos rotation will be bumped back a day. Jered Weaver will start on Tuesday night against the Red Sox, followed by Joel Pineiro on Wednesday afternoon. Ervin Santana will open a series against the Rangers on Friday night.
Haren, 29, 7-8 with a 4.60 ERA this season, moves to the American League West, a division that will be familiar thanks to his time in Oakland. He pitched for the A's from 2005-07, going 43-34 with a 3.64 ERA.
The Halos aren't just showing off their newest acquisition on Monday night. With Boston's powerful lineup in town, the Angels will need Haren right away.
Bailey Stephens is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.