He thinks of how he could pitch for the Dodgers, about 30 miles from his alma mater, Mater Dei High in Santa Ana. Or how Vin Scully might tell a story or two about him as he comes out of the bullpen. Or what it might be like to be part of the team that wins the franchise's first World Series in 27 years.
First he'll have to make the team. Santos saved 30 games for the Chicago White Sox four years ago, but he isn't guaranteed a place on the Dodgers' opening-day roster. The 31-year-old right-hander will be one of about 20 players in camp this spring on minor league deals, his status a reflection of injuries and decline in performance over the last three seasons.
But this isn't the first major crossroads Santos has faced in his career. Originally a shortstop, he converted to pitching when it became apparent that he would never hit well enough to be a major league position player.
"I feel that has prepared me for any challenge that can come," Santos said in a phone interview from his home in Scottsdale, Ariz.
If Santos makes the Dodgers' roster, he would be the third converted position player in the team's bullpen, alongside closer Kenley Jansen and newcomer Chris Hatcher, who were catchers. But neither Jansen nor Hatcher were ever as highly regarded as a position player as Santos.
At Mater Dei, Santos, 6 feet 3 and an impressive-looking athlete, was labeled a can't-miss prospect, drawing comparisons to Alex Rodriguez.
"The best prospect I have ever seen," said his agent, Joe Longo. "He was bigger than everybody, but was so quick laterally."
Even after an underwhelming season as a high school senior, he was still a first-round selection in the 2002 draft. The Arizona Diamondbacks picked him 27th overall.
Over the next couple of seasons, Santos looked as if he was on a fast track to the majors.
He was promoted to double A shortly after his 19th birthday in 2004. Later that year, he played in the Arizona Fall League with and against baseball's top prospects, many of whom were in the majors the next season.
Santos said he believed "in my heart of hearts" he was destined to have a 15- to 20-year big league career. But he hit a wall in triple A, where his offensive shortcomings became pronounced.
He gradually morphed from top prospect to minor league journeyman. He was traded to the Toronto Blue Jays in 2005 and claimed off waivers by the Minnesota Twins three years later, never receiving a call-up to the major leagues.
By this time, Santos was married to his high school sweetheart, Kristin. Two of their three children were already born. His $1.4-million draft bonus spent, Santos worked construction jobs in the off-seasons. Kristin sold her engagement ring.
"Now, I'm playing to put food on the table for my family," Santos said.
His career might have come to an end in the off-season leading up to the 2009 season if not for Longo asking Dennis Gilbert to give Santos a chance. Gilbert was then a senior adviser for the White Sox.
"I always liked his arm and I liked his work ethic," Gilbert said. "And I liked Joe."
Santos received an invitation to the White Sox's spring-training camp but again failed to make the opening-day roster.
That's when former major league manager Buddy Bell, the White Sox's vice president of player development, asked Santos whether he would be open to pitching.
Santos knew he could throw in the mid-90s, but initially resisted the idea. He still believed his talent could get him to the major leagues as a shortstop.
"I was only 25," Santos said.
Santos moved on to the San Francisco Giants' camp, but didn't stick there, either. The White Sox asked again whether he would consider pitching.
"I didn't get sleep for a good four nights," Santos said. "It was the hardest decision I've ever had to make."
This time, he agreed.
When the White Sox broke camp, Santos remained in extended spring training with players who were mostly between the ages of 17 and 21.
He spent the year in the minor leagues, reaching triple A by the end of the season. The numbers weren't pretty — he had an earned-run average of 8.16 across four levels — but he knew he was making progress.
In 2010, he made the opening-day roster, changing his family's fortunes.
With Santos drawing what was then the major league minimum salary of $400,000, Kristin said, "I could buy plane tickets to go see him. It was insane to be able to spend that kind of money."
Santos made his major league debut April 8, pitching a scoreless seventh inning. It was the first of 56 appearances he made that season, and he finished with a 2.96 ERA.
The next year, he became the White Sox's closer and saved 30 games. His reward was a three-year contract guaranteed for $8.25 million, but shortly after signing him the White Sox traded him to the Blue Jays.
In three seasons with Toronto, Santos was limited to 61 games because of shoulder and elbow problems. He became a free agent this off-season when the Blue Jays declined his $6-million option for 2015.
Santos could have signed with teams that were short on bullpen depth, but he felt confident enough about his arm to compete for a place on the Dodgers' $260-million roster.
The Dodgers are hopeful. General Manager Farhan Zaidi said Santos' transformation from infielder to pitcher is an indication of more than resilience. It's also evidence of his athleticism.
"Guys that are athletic can make adjustments," Zaidi said.
Santos already has.
Follow Dylan Hernandez on Twitter @dylanohernandez