There were so many players who I wished I could have included on this list, so I'll include them here in the honorable mentions.
Already a key member of the Cardinals bullpen, Thompson could end up becoming a valuable starter for St. Louis in the near future. Even if he does not end up landing in their rotation, he represents a very important piece for the future of their late-inning group.
While he may not have the kind of ceiling that some other pitching prospects in the organization have, McGreevy could be a cost-controlled rotation piece for St. Louis as soon as this year. In 24.2 innings this year, McGreevy has a 2.19 ERA and was called up to Memphis recently because of that.
Not a name many Cardinals fans know already, but at just age 18, Mejia has the potential to jump up the Cardinals' prospect ranking in a hurry if his development continues as it has. Last year, in the Dominican Summer League, Mejia's 145 wRC+ ranked in the 90th percentile amongst 17-year-olds at that level. Mejia is a shortstop with raw power and could be a legit slugging threat with good defense in the future. I wouldn't be surprised to see him as a trade piece this year either.
Yepez can hit, and whether it's with St. Louis or another club, his bat needs to be in a Major League lineup sooner rather than later. He posted a 110 OPS+ last season in 76 games with St. Louis, and so far in Memphis this season has a .917 OPS. The tricky part is finding a position for him, but the bat plays.
Burleson had a very quick rise through the Cardinals' system and made his MLB debut toward the end of the 2022 season. The Cardinals are very high on his ability to hit, and his left-handed bat landed him a spot on their Opening Day roster. Early on this season, Burleson has seen significant playing time against right-handed pitchers, and represents a very valuable bat long-term.