Of course, it seems fair to allow only the best record teams into any playoff structure, but with unbalanced schedules and division formats, we cannot really be sure a better record is a better team, unless they are many games ahead.
Fans want to see their team in the playoffs, and fans from an inferior team that made the playoffs from a crappy division, probably don't care much the kept a better team out. Either way, more teams means more money, and we know that's what it is all about. That's what it's always been about. The randomness of baseball makes it more likely underdog teams can win any given series, and the smaller the series, the better chance they have. When inferior teams win, it does cheapen the meaning of the 162 game season and the efforts put out bu the better teams, but money will always trump fairness, and if the fans enjoy it more, there will be no stopping it.
There are ways to level the playing field, but traditionalists are already pissed at many of the recent changes to the game, including the DH (not so recent, except for the NL expansion,) no shifts, pitch clocks...
A totally balanced schedule, or getting closer to one would help keep weaker teams out, if you also do away with the 3 division structure and the rule that all division winners get a playoff slot. I know many fans already hate interleague play, but the unbalanced schedules and divisions are the major cause for teams like the 2006 Cardinals even getting a shot at winning it all. Some might argue the 2006 Cardinals give hope to all decent but undeserving teams and fans, but if the idea is to be as fair as possible while giving the fans what they want, and the owners more money they want, then major changes might be needed.
Here is one plan that could be used:
1. Make 3 regional divisions of 10 teams. (If MLB ever expands to 32 teams, it could be 4 divisions of 8 teams.) It would be highly unlikely a division winner doesn't have a top 16 record. There is no AL and NL.
2. 16 teams make the playoffs: 3 division winners + 13 WC teams. They are seeded by record, not by division winner status.
3. All playoff rounds are 7 games, which would help minimize the "luck factor." This would also increase the amount of playoff games and create more excitement for fans and more money for the owners and players who make the playoffs.
The schedule would be the bitch. Everyone playing the exact same amount of games vs everyone else is impossible, unless they change the amount of games in a season. (162 games/ 29 other teams does not create a whole number. It's 5.59.) Some sort of minimal unbalanced structure would have to be designed. 5 games vs 12 teams and 6 games vs 17 teams. Some obvious points of contention would arise, such as the taking away of so many interdivisional rivalry games during a season, and how much attendance, viewership and fan excitement would be reduced, during the season. How are the 5 games vs 6 games determined? (Previous season records? Rotating teams, so over a certain amount of seasons, it becomes more "leveled?")
Maybe you always play 6 games vs your 9 other division foes and then 5 vs 12 other division foes and 6 vs 8 others, but still that makes for just one home series of 3 games vs the Yanks for Sox fans.
Another schedule idea would be to move away from as balanced a schedule as can be made but still a more balanced schedule than we have, now:
8 games vs 9 division foes (72 games) + 4 games vs one other division and 5 games vs the other division (90 games.)
10 games vs 9 division foes (90 games) + 3 games vs 8 other teams and 4 games vs 12 other teams (72 games)
Or, you just shorten the season, since the playoffs will be expanded.
Going to 16 teams without changing the 3 division and 2 different league set-up seems like it will further mess up the fairness while cheapening the value of the 162 game season. I guess with 8 teams making the playoffs in each league, it would make it almost impossible for a division winner to NOT have a top 8 record, so there would likely never be a 2006 Cardinals team, again, but it would still remain unfair (but less so) for teams in much better divisions.
If we applied the 16 game playoff structure to 2023, the Mariners and Yankees would have made the playoffs. The Sox and Guardians would have stayed in the race longer and missed by 4 games. If you seeded by record only, it would have been 7 game series between these teams:
1. BAL vs 8. NYY
4. TEX vs 5. TOR
2. TBR vs 7. SEA
3. HOU vs 6. MIN
Another thing that could be done to add more value to the regular season, would be to re-seed the bracket after every round, by regular season record, so if a low-seeded team wins round one, they'd face the best remaining team in round two.