Whether or not the St. Louis Cardinals earn a playoff spot by the time the regular season comes to a close, the 2026 season has done a lot of good for the organization. When the Cardinals traded Brendan Donovan, Nolan Arenado, Sonny Gray and Willson Contreras, it was a clear sign that the 2026 season was going to be about development, above all else. Now, of course, that doesn't mean that the Cardinals don't try to win every game. Throughout the first half of the season, it was talked about left and right now the club was playing significantly above expectations. The second half of the season unfortunately hasn't been the same and the club sold off more pieces, including Lars Nootbaar, JoJo Romero and Dustin May. Again, the story of the season is development for young guys and seeing who should be a part of the core moving forward, and who shouldn't be. From that perspective, the Cardinals have definitely learned a lot. With that being said, he are four players who should be core pieces moving forward and three who shouldn't be.Core PiecesJJ WetherholtAug 17, 2026; Cincinnati, Ohio, USA; St. Louis Cardinals second baseman JJ Wetherholt (26) runs off the field at the end of the first inning against the Cincinnati Reds at Great American Ball Park. Mandatory Credit: Katie Stratman-Imagn Images | IMAGN IMAGES via Reuters ConnectLet's start with the most obvious one. Wetherholt entered the season with massive expectations, despite the fact that he's a rookie. He has somehow outperformed all expectations. Wetherholt has been great offensively and even better defensively. Wetherholt should be in line for the National League Rookie of the Year Award and a Gold Glove Award at second base. Plus, he already has the long-term contract. He is the biggest building block for the organization. Jordan WalkerAug 20, 2026; Cincinnati, Ohio, USA; St. Louis Cardinals outfielder Jordan Walker (18) reacts after hitting a three-run home run in the third inning against Cincinnati Reds at Great American Ball Park. Mandatory Credit: Katie Stratman-Imagn Images | IMAGN IMAGES via Reuters ConnectWhen the 2026 season began, this may not have been the case. But Walker has firmly cemented himself as a piece to build around, right up there with Wetherholt. These two together should be the centerpieces of the Cardinals for years to come. Still just 24 years old, Walker has figured it out. He's batting .285 with 27 homers. 96 RBIs, 18 stolen bases, and 28 doubles in 129 games played. There have been few offensive weapons better in 2026. Alec BurlesonAug 19, 2026; Cincinnati, Ohio, USA; St. Louis Cardinals first baseman Alec Burleson (41) scores on a single by center fielder Nathan Church (not pictured) during the fourth inning against the Cincinnati Reds at Great American Ball Park. Mandatory Credit: Tanner Pearson-Imagn Images | IMAGN IMAGES via Reuters ConnectAlthough Burleson is older than Wetherholt and Walker, he should be in the mix for a long-term spot as well. Burleson has developed into one of the best offensive first basemen in baseball. He's batting .291 with 21 homers, 96 RBIs and a league-leading 33 doubles. Masyn WinnAug 18, 2026; Cincinnati, Ohio, USA; St. Louis Cardinals shortstop Masyn Winn (0) throws to first to get Cincinnati Reds outfielder Hector Rodriguez (not pictured) out in the