Valid points. I do think DeJong has the ability to be a .800-plus guy and that would give the Cardinals three, if Ozuna was retained. As you note, these fellows are not easily obtained. So you have to make do in other ways such as situational hitting, defense, bullpen and better starting pitching.
I don't think all title teams will have three players with .900 OPS material. Try as they might, the Yankees and Dodgers haven't won any World Series lately, notably the Dodgers, although the Dodgers may have what it takes this year.
This type of player is valuable but you almost have to get lucky from within. For now, all the Cardinals can do is win the division or make the playoffs Then they go from there. Do they have enough to challenge the Dodgers? Well, you would say no except for the fact that the teams played four games in April and the Cardinals won all four.