Michael Wacha
Shelby Miller may have put together the more complete 2013 season for the Cardinals, but it was Michael Wacha who stole the show for them toward the end of that campaign.
In 15 appearances (9 starts), Wacha went 4-1 with a 2.78 ERA in 64.2 innings and pitched his way into the Cardinals' playoff rotation. His final regular-season start saw him take a no-hitter into the 9th inning against the Nationals, and then he followed that up by taking a no-hitter into the 8th inning against Pittsburgh again to force Game 5 of the NLDS.
Wacha was masterful in the NLCS against the Los Angeles Dodgers, throwing 13.2 scoreless innings across two starts and earning NLCS MVP honors. Things unraveled for him in the World Series though as the Cardinals fell to the Boston Red Sox.
Wacha came back strong in 2014 and 2015, posting a 3.31 ERA over 288.1 innings of work, and like the other names on this list, looked like he could be "the guy" for St. Louis for a long time. Unfortunately, shoulder injuries got the best of Wacha, and the final four seasons of his Cardinal career ended with just a 4.39 ERA in 514 innings.
Since leaving St. Louis, Wacha has bounced around a little bit, really getting his career back on track with Boston in 2022 and becoming one of the Padres' best pitchers in 2023.
At the beginning of this story, I talked about how it's crazy that the Cardinals did not end up with multiple front-line starters over the years. Although some had small runs with the club and other's realized that potential fully elsewhere, each name on this list leaves a bit of disappointment in the heads of Cardinal fans, knowing what "could have been".