Santiago started his Angels career 0-6 with a 5.19 ERA, but he posted a 3.30 ERA over a 90-inning stretch after coming back from a three-week stint in Triple-A. Now the 27-year-old left-hander will have to fight off a couple of young up-and-comers to keep his spot in the rotation.
Several dark-horse candidates could emerge throughout the course of Spring Training -- like Cory Rasmus, Drew Rucinski, Jose Alvarez or one of the non-roster invitees -- but it'll mainly be Andrew Heaney, Nick Tropeano and Santiago battling it out.
And there's no telling which way it'll go.
"There's going to be some competition and we're going to see how it plays out," Angels pitching coach Mike Butcher said. "There's some definite opportunities for guys to make an impact in our rotation this year."
Heaney is the new prize of the system, a guy the Angels obtained by trading Howie Kendrick. He's 23, three years removed from being the ninth-overall pick by the Marlins and a few months removed from a humbling debut in the Majors that saw him post a 5.83 ERA in 29 1/3 innings.
Heaney -- with a 2.69 ERA, a 1.13 WHIP and a 3.71 strikeout-to-walk ratio in his Minor League career -- believes failing in the big leagues prepared him for the biggest spring of his life.
"It helped a lot," Heaney said. "I'm always going to be grateful for getting that opportunity to be able to go up there and experience it and face those kind of hitters and get kind of picked on a little bit."
Tropeano is also coming off his first taste of the Majors, a four-start stint that saw him post a 4.57 ERA with the Astros. In Triple-A that year, the 24-year-old right-hander finished with a 3.03 ERA and a 0.99 WHIP in 124 2/3 innings, a stretch that saw him turn his changeup into a legitimate out pitch.
"It's going to be a healthy little competition," said Tropeano, who was acquired for Hank Conger in November. "Obviously we're all on the same team here. It's going to be fun."
Competition is nothing new for Santiago. He's had it every spring, and in each of his three full seasons in the Majors, his role has been fluid. Santiago would likely be used out of the bullpen if he doesn't win a spot in the rotation, but that certainly isn't his preference.
"I definitely want to be in the rotation," Santiago said. "I didn't train the whole offseason for one inning. I threw 92 pitches right before camp -- and I hope I don't have a one-inning, 92-pitch outing."
What Santiago is hoping for is a longer leash.
Down the stretch, he didn't necessarily have it -- partly because he struggled so much early in the year, partly because the Angels' bullpen became such a strength. Often times over the last couple of months, Santiago would be cruising through a start and get pulled well before reaching triple digits with his pitch count, even though he has more stamina than most pitchers.
It only really bothered him once, on Aug. 17 in Arlington, when he needed only 87 pitches to twirl six innings of one-run ball and was taken out before the seventh inning of a one-run game.
"I wanted to go into [Angels manager Mike Scioscia's] office, just to talk to him, say something," Santiago said.
But he never did. Santiago left it alone and did his best to flip the page, opting not to create any distractions in the stretch run of a first-place season.
He'll just hope to gain more trust in camp.
"It's definitely a competition," Santiago said. "You don't trade Kendrick for no reason."