Those hopes were dashed Friday when Tatis received an 80-game suspension after testing positive for a performance-enhancing substance.
With the suspension effective immediately, Tatis will not play in the majors this season and will then miss the first 32 games next season.
MLB said Tatis tested positive for Clostebol, a performance-enhancing substance.
"I've been informed by Major League Baseball that a test sample I submitted returned a positive result for Clostebol, a banned substance," Tatis said in a statement through the MLBPA.
"It turns out that I inadvertently took a medication to treat ringworm that contained Clostebol. I should have used the resources available to me in order to ensure that no banned substances were in what I took. I failed to do so.
"I want to apologise to Peter, AJ, the entire Padres organisation, my teammates, Major League Baseball, and fans everywhere for my mistake. I have no excuse for my error, and I would never do anything to cheat or disrespect the game I love."
Tatis has yet to play this season after breaking his left wrist, reportedly in a December motorcycle accident in the Dominican Republic. He had surgery in mid-March and began a minor league rehabilitation assignment on Aug. 6.
"Obviously, everybody's very disappointed. Somebody that from the organization's standpoint we invested time and money into," Padres general manager A.J. Preller said.
Tatis was an All-Star last season when he hit .282 with a NL-leading 42 home runs and 97 RBIs.
He becomes one of the most prominent players penalized for PEDs, joining the likes of Alex Rodriguez, Manny Ramirez, Robinson Cano and Miguel Tejada.
The Padres entered Friday 63-51 and hold the final of three NL wild-card spots. They recently acquired superstar Juan Soto from the Washington Nationals and hoped to have Tatis join a formidable lineup with Soto and All-Star Manny Machado.