The 2015 season was one big advertisement for the dynamic nature of Major League Baseball's competition.
There wasn't one club that made a big difference. There were seven clubs that made a big difference.
What they demonstrated was the vitality of baseball's competitive balance and the overall health of the game. There were some distinct surprises, but the success of none of these clubs was anything remotely like a fluke.
So, league by league, in alphabetical order. In the American League:
Two years ago, Houston lost 111 games. But here it was, winning 86 games, qualifying for the postseason and defeating the former owners of October, the Yankees, in the AL Wild Card Game. The Astros then took the eventual World Series champion Royals to five games in a thrilling AL Division Series.
The Astros rebuilt an organizational structure from the ground up and now appear to be set for a very bright future. This was a turnaround, remarkable in both its extent and its speed.
Kansas City Royals
The Royals won a World Series for the first time in 30 years, one year after reaching the postseason for the first time in 29 years. This was another victory for tried-and-true organizational traits of astute scouting and diligent player development, combined with mid-range acquisitions at the Major League level.
Two decades ago, the game's economic structure probably wouldn't have allowed a small-market franchise to succeed to this extent. Baseball's economic playing field still isn't exactly level, but it has been altered enough so that a club from Kansas City can succeed through intelligent decision-making.
In what was expected to be a ferocious race in the AL Central, the Twins were picked to finish either fifth or in the International League. Losers of more than 90 games for four straight seasons heading in 2015, the Twins are in the process of restoring their status as a role-model franchise, with a strong base of their own young talent mixed with astute acquisitions.
The Twins put up a winning record in 2015, finished second in the AL Central and they were in the hunt for a postseason berth until the final weekend of the season.
Toronto Blue Jays
The circle was unbroken when the Blue Jays qualified for the postseason for the first time since 1993. Toronto won consecutive World Series in 1992-93, but in 2015, it became the 30th franchise to qualify for the postseason in this young century. Every club has been in the postseason over the last 15 years. That looks a lot like competitive balance and inclusion.
In an era of increased pitching dominance, the Blue Jays had an offense that led the Majors in runs scored with 5.50 per game. They won the AL East handily, by six games, and they made October baseball once again a North American event.
In the Senior Circuit:
It has been 107 years since the Cubs won the World Series. But when the preseason prognostications appear early next year, we can fearlessly predict that many people will pick the Cubs to end that drought.
Why? Because the Cubs improved by 24 games in 2015, becoming a 97-victory team, a National League Wild Card team, a team with the third-best record in the Majors. Then, in the NL Series, they defeated their archrivals, the Cardinals, who had led the Majors with 100 victories.
True, the Cubs were subsequently swept by the Mets in the NL Championship Series, but with all of Chicago's wonderful young talent, and with some impressive offseason additions, the Cubs have completely reversed their historic course. The perception of the Cubs as a powerhouse team may require some adjustment, but it provides more evidence of just how much the baseball landscape can change.
New York Mets
The Mets had not had a winning record since 2008, but in '15, New York won 90 games, the NL East and the NL pennant. In the process they displayed a supremely talented group of young starters that were the envy of roughly 29 other teams.
The Mets may have been down for a time, but there is reason to believe that they are now going to be up for the foreseeable future.
OK, the appearance of the Pirates in the postseason is no longer a surprise. They have been there in three straight seasons. But the overall changes in the game that allow the Pittsburgh franchise to succeed are a relatively recent development.
The Pirates won 98 games in 2015, for the second-best record in baseball. It was also the second-best record in the NL Central, which left the Pirates in the NL Wild Card Game. But this franchise, another small-market operation, has become highly successful because it has an opportunity to succeed on the basis of baseball intelligence, not simply on depth of pockets. It's still not easy, but the Pirates, who went two decades without a winner, are proving that it can be done, with a sound organization that makes fundamentally sound decisions.
So 2015 was a truly memorable season, in part because losing teams suddenly morphed into postseason teams. This is precisely the kind of thing that makes you eager to see what the 2016 season can do to top this.
Mike Bauman is a national columnist for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.