4. Brendan Donovan
The Cardinals seem to be masters at producing under-the-radar prospects who come up to St. Louis and far exceed expectations. Brendan Donovan is one of the latest examples of that.
Coming into 2022, Donovan was the Cardinals' 12th-ranked prospect and was seen as an above-average hitter with below-average defense but versatility to play six positions. Donovan came up that year and instantly became a regular for the contending club, posting a 128 wRC+ in 126 games for St. Louis while winning the first-ever Utility Gold Glove.
He followed that up with another promising season in 2023, but his true potential was cut short by a frustrating elbow injury that sidelined him from the end of July through the remainder of the season. Donovan started the year slow, but from May 23rd until July 29th when he was shut down, he posted a .316/.395/.489 slash line with a 145 wRC+.
Donovan's truly elite on-base skills and continued improvement in both the contact and power departments make him the clear choice to leadoff games for the Cardinals in 2024, and he's quickly become one of the most valuable Cardinals in this organization.
Donovan will not hit free agency until 2028 and is in his final pre-arbitration season, giving the Cardinals a cheap and powerful weapon they can deploy all over the field on any given day.
Donovan's biggest "flaw" as a player right now is the drop-off in production against left-handed pitching. While he's posted a .801 OPS and 128 wRC+ against right-handed pitching in 699 plate appearances, he's closer to league-average against right-handed pitching with a 102 wRC+. He has an identical .381 OBP against both right and left-handed pitching, so it's really only a matter of adding a bit more power against southpaws to balance things out.
Donovan continues to be massively underrated by many, but given a full season in 2024, it will be hard for anyone to ignore how great of a player he already is.