I'm a pretty casual baseball fan, but here's my $0.02:
The biggest story this year for the Cards has been starting pitching IMO. The Cards have been decimated by injuries this year, particularly their starting pitchers (and starting pitching was already considered a weakness going into the season). Wainwright has been their best and most consistent starting pitcher all season, when ideally he is your 4-5th best guy. Lol at his game tonight, that was just incredible. Flaherty, Mikolas, and Kim have all missed significant time, and at this point it's probably too late in the season to make a push for the playoffs.
The outfield is made up of youngish/talented players: O'Neil - Bader - Carson. Bader (27) is electric defensively, but inconsistent at the plate. O'Neil (26) is a stud. Carson (22) is a switch hitting rookie and looking great so far.
The Cards have 2-3 likely future HOF players in Arenado (3B), Goldschmidt (1B), and Yadi (C). At 39, Yadi is still a great player but is close to retirement at this point, likely only has 1 or 2 more years left. Goldy is still a very good player, but at 33 is on the tail end of his career. Arenado is a bit younger at 30 and still a legit superstar. All 3 are elite defensively.
Edman (2B/OF) and DeJong (SS) are pretty "meh" IMO. I want to love Edman, but he's been frustrating to watch this year. He has great speed, can switch hit, and can play multiple positions, so he is no doubt a useful player. Still relatively young at 26 so maybe he can still improve and make an impact. DeJong is generally solid defensively but weak offensively. He's also in the midst of a particularly bad offensive slump right now.