The St. Louis Cardinals loaded up on college talent during the third day of the 2021 MLB Draft, selecting collegiate players with nine of their final 10 picks.

Switch-hitting shortstop Mack Chambers (11th round, No. 331 overall) was the Cards' first pick of the day. Chambers transferred from Seminole State College to the University of New Mexico this year and had a dominant season for the Lobos, hitting .371 with a 1.067 OPS, seven homers and 31 RBIs in 41 games.

In the 12th round (No. 361 overall), the Cardinals selected left-hander Chris Gerard from Virginia Tech University. The 5-foot-10, 175-pound lefty had a strong three-year career for the Hokies, posting a 2.63 ERA with 121 strikeouts and 41 walks over 24 starts (120 innings). Gerard was ranked 332nd on Baseball America's top 500 draft prospects list.

The Cardinals took another college lefty in the 13th round (No. 391 overall), Wofford University's Hayes Heinecke. The 6-foot, 210-pound left-hander had an outstanding freshman season, leading the Southern Conference with 10 wins and ranking 14th in Division I, and finished his collegiate career with a 15-7 record and a 2.98 ERA, striking out 163 batters over 157 innings pitched. Heinecke rated 316th on Baseball America's draft prospect rankings.

St. Louis selected a big right-hander in the 14th round (No. 421 overall), 6-foot-5, 245-pound Andre Granillo from UC Riverside. Granillo, who had a 5.98 ERA over 42 college games, is currently playing for Cotuit in the Cape Cod League, where he has a 2.45 ERA with 17 strikeouts and two walks in 11 innings.

The Cards picked another pitcher from a Southern California college in Round 15 (No. 451 overall), taking lefty Alex Cornwell from USC. Cornwell, who was previously selected by the Chicago Cubs in the 37th round in 2017, had a 5.02 ERA with 79 strikeouts and 26 walks over two seasons for the Trojans.

In the 16th round (No. 481 overall) the Cardinals selected their lone catcher of this year's draft, Aaron McKeithan of UNC Charlotte. McKeithan’s head coach at UNC-Charlotte was Robert Woodard, a former University of North Carolina pitcher and St. Louis Cardinals draft pick (46th round, 2006, did not sign), who was coached by Cardinals manager Mike Shildt at “On Deck” training facility during his high school years.

With their 17th-round pick (No. 511 overall), the Cardinals selected outfielder Elijah Cabell from Florida State. Cabell hit 29 home runs over three seasons with the Seminoles, including an iconic blast against Pittsburgh on February 28 of this season that traveled 489 feet, which would tie for the longest home run ever hit at Busch Stadium III. Cabell previously was drafted by the Milwaukee Brewers in the 14th round of the 2018 draft. Cabell ranked 387th on Baseball America's draft prospect rankings.

The Cardinals selected University of Connecticut right-hander Andrew Marrero in the 18th round (No. 541 overall). The 5-foot-10, 196-pound righty had a 5.19 ERA with 34 strikeouts and nine walks over 22 relief appearances spanning two seasons for the Huskies.

In the 19th round (No. 571 overall), the Cardinals selected a hitter from East Carolina University for a second straight year, taking first baseman Thomas Francisco. He follows 2020 second-rounder Alec Burleson, who is now with Double-A Springfield. Francisco played three seasons at ECU, batting .348 with 18 home runs and 81 RBIs while helping the Pirates to two NCAA regional championships.

The Cardinals' final pick of the draft and their lone high school pick on Day 3 was third baseman Xavier Casserilla, a 20th-rounder (No. 601 overall) selected out V.R. Eaton High School in Haslet, Texas. The Wichita State commit was a First Team District 4-6A selection in 2021. Casserilla batted .375 his junior season and was 2-0 with a 1.16 ERA on the mound, showcasing a fastball that topped at 96 miles per hour.

In total, the Cardinals selected 21 players over the three-day event, including 18 collegians and three high school preps. The players represented 12 states, with six players hailing from California and three from New Jersey. The Cardinals' selections by position included eight right-handed pitchers, four left-handers, a catcher, four infielders and four outfielders.