Latos is expected to provide length out of the bullpen, but could possibly make a spot start if needed.
"We need arms that are going to help us win games, hold leads," said Angels manager Mike Scioscia, his team a half-game behind the Astros for the second American League Wild Card after Monday's 5-4 win. "You need guys to give you innings if you need it, but we brought Latos in here to hopefully do something that's going to help us get into the playoffs, whatever role he's in."
The Angels are without their two best relievers, closer Huston Street and setup man Joe Smith, while starters Jered Weaver and Matt Shoemaker nurse arm injuries.
Street will miss the rest of the regular season -- but is holding out hope for the playoffs -- with a Grade 1 strain of his left groin, while Smith is confident he can return from his sprained left ankle by Sunday.
Shoemaker was scratched from his Tuesday start, replaced by Nick Tropeano, because of lingering stiffness in his right forearm. The 29-year-old right-hander isn't sure when he'll throw off a mound again, but said Monday he's "hopeful" of pitching this season and said his arm was feeling "much better."
Weaver experienced some shoulder stiffness in his Sunday start against the Mariners, lasting only five innings and 71 pitches, but Scioscia was "optimistic" Weaver would take his turn Friday against the Rangers.
Journeyman starter Jo-Jo Reyes also joined the Angels on Monday, but hasn't been added to the 40-man roster. The 30-year-old left-hander hasn't pitched in the big leagues since 2011, but finished the season with the team's Triple-A affiliate, posting a 4.76 ERA in 68 innings, and will work out with the Angels in case they need him.
With Latos, the Angels have 39 active players. To create room on the 40-man roster, catcher Rafael Lopez was recalled from Triple-A Salt Lake and transferred to the 60-day disabled list with a fractured left hand.
"Some guys on our pitching staff have been stretched, they've pitched a lot, and we especially need rotation depth with Shoemaker up in the air," Scioscia said. "Latos gives us an option and some depth, and we'll see how we use him this week."
With the Padres from 2009-11, Latos posted a 3.37 ERA, a 1.15 WHIP and a 3.06 strikeout-to-walk ratio, averaging nine wins, while making 24 starts per season. With the Angels, Latos will make the Major League minimum for seven or eight days, then hit the free-agent market once again over the winter.
Latos has only played catch since his last appearance with the Dodgers 13 days ago, but was expected to throw off a mound on Monday and can be available by Tuesday.
"His stuff is real; his stuff is good," Scioscia said. "When he pitched against us he was really effective, so you saw his potential to pitch well, so we'll see how it plays out."