Super utility man Tucupita Marcano
This one is a bit different from Swaggerty and Castillo. That is because while this player did make their MBL during the 2021 season, they still have yet to make their debut with the Pittsburgh Pirates. So while they would not be making their MLB debut by cracking the Opening Day roster, they would still be making their Pirate debut.
When the Pittsburgh Pirates traded Adam Frazier to the San Diego Padres in July the center piece of the trade was essentially Adam Frazier 2.0. Who was that player? Tucupita Marcano. Like Frazier, Marcano is contact first, left-handed hitter who can play all over the field. However, Marcano, unlike Frazier, can also play third base and shortstop in addition to second base and the outfield.
The Pirates are very high on Marcano. They attempted to acquire him in the Joe Musgrove trade, but the Padres did not want to move him at that time. To be honest, the Padres were likely only willing to move him I the Frazier trade because Frazier essentially replaces Marcano in their organization through the 2022 season.
With the Pirates remaining high on Marcano and him already having a cup of coffee in the Majors, it would be more of a surprise if he did not crack the Opening Day roster than it would be for him to make the team. Marcano is a player Pirate fans will likely see a lot of in 2022.