Last year, the Cardinals had one starting pitcher with an above average season. Their second best starter, Kwang-Hyun Kim, is now a free agent. They are relying on two pitchers who barely pitched last year, Dakota Hudson and Miles Mikolas, plus a third pitcher in Jack Flaherty who missed half the season. Their most reliable pitcher of the last few years will be 40-years-old. You could make the case that their safest pitcher then is Steven Matz. To me, they unquestionably need another starter.
The Cardinals seem to disagree or at least they seem to publicly disagree and privately hope to improve.