MLB: Are the best getting better and the worst getting worse?

Do you remember June? Glorious, glorious June when the odds the Mariners made the playoffs were above 75% and the Oakland A’s were a mere speck in our rearview mirrors? It was around then that I began to notice something weird about the playoff race, or rather, the lack thereof. The A’s were goners, 7.5 games back in the Wild Card. The Mariners were comfortably above .500 and, it seemed they would cruise to the second Wild Card spot. The Astros, Indians, Red Sox and Yankees faced little competition from the rest of their divisions and as the season progressed, these top teams only got better. It seemed each playoff team would stroll into October. That is happening now, at least in the AL, where the Mariners and Rays sit well back of Oakland in the Wild Card. The NL is slightly more exciting, with the NL West and Central races tightening.

What piqued my interest about this lack of drama was that it felt that the league was more polarized than ever. The good teams seemed better and the worst teams seemed worse than in previous seasons. The differences between the best teams, the average teams, and the worst teams seemed to have grown. Teams like the Red Sox and Orioles seemed like once-in-a-decade collections of talent and ineptitude, respectively. So, as a numbers nerd, I started looking at the data.

First, I looked at the win percentages of the best teams in the league for every season since 1995. To make sure that the data did not get skewed by absolutely dominant single teams (2001 Mariners, where u at?) and to give a better picture of the data, I averaged the win percentages of the best six teams, the best five teams, the best four teams, etc, down to the best single team. The chart below compares the win percentages of the best teams each season to the win percentages of the best teams in 2018.

The top teams in 2018 were consistently better than the top teams in previous seasons. The size of the gap varies, but the top six teams in 2018 have a higher win percentage by 0.021 points, or approximately 3.5 more wins over a season. The best three teams won about five more games and the best team in the league is on pace to win about 9 more games than the average best team in the league from 1995 to 2017.

Meanwhile, the chart to the right shows the win percentages of the best teams in the MLB since 1995. The cells highlighted in red are greater than the win percentage of the teams in 2018.

Only twice since 1995 have the best six teams in the league had a higher combined win percentage than the best six teams in 2018: in 1998 and 2002. 2002 was the most recent year that the best teams in the league have been as good as they are in 2018, and even then, it is only the 6th and 5th best teams in the league that have been better. In 2001, only the 3rd and 2nd best teams as well as the top team were better than in 2018 (Shouts to Aaron Sele, Ichiro, Mark McLemore and co.). So at least half of my hypothesis is correct: the best teams in the league this year were better than the best teams in the league in past years. But the same kind of analysis should be done on the worst teams to see if the bad teams in 2018 stand out as much as the good teams:

The differences between the worst teams is even larger than the differences between the best teams. The worst six teams in the league have been 0.034 points worse than the worst teams from 1995 and 2017, which is 5.5 games worse over a season. The worst three teams have been 7.3 wins worse and the worst team is on pace to finish 12.5 wins worse than the worst team in the league. Pour one out for the Orioles fans in your lives.

The chart to the left shows the win percentages of the worst teams in MLB since 1995. The cells highlighted in red is lower than the win percentage of the teams in 2018.

So, the worst teams are really bad this year. Only twice since 1995 have the worst teams in the league been as bad as the worst teams in the league in 2018. Only the worst four teams in 2002 were worse than the worst four teams in 2018, and the worst team in 2003 was worse than the worst team in 2018. Hey O’s fans, cheer up! At least you’re not the 2003 Detroit Tigers (that’s one of their random, nameless ‘03 pitchers nursing a headache below).

Now that it has been established that the best teams in 2018 are better than most of the best teams from 1995 to 2017 and the worst teams in 2018 are worse than almost all of the worst teams from 1995 to 2017, I combined those numbers to see how polarized the league has become, and if it is more so than it has been since 1995. To do so, I subtracted the Win% of the best teams from the Win% of the worst teams to measure the size of the difference, (below) in wins, between the groups of teams.

The difference between the best six and the worst six teams in the MLB from 1995-2017 is, on average, almost 31 games. In 2018, the difference is almost 40 games. The gap between the best and worst three teams in the league, is a little over 12 games larger in 2018 than the gap from 1995 to 2017. For the best and worst teams, the difference in 2018 is 21 games larger than the difference from 1995 to 2017.

The chart to the right shows the difference between the best and worst teams for each year, the cell shaded red is greater than the difference in wins for 2018 teams.

Only the best and worst six teams in the league in 2002 had a bigger gap in the number of wins as in 2018. A single point of data out of 138 total differences in wins is larger than the difference in wins in 2018. I am pretty confident in saying that the league in 2018 is much more polarized than it has been for the last twenty four years.

Here is a different way of looking at the data. This chart that presents all of the data in the previous table: the size of each smaller colored bar represents the difference in win percentage for that grouping of teams. Each larger, multi-colored bar represents a year.

This allows the differences between the best and worst teams, or what I am calling polarization, to be seen over time. Polarization is highest in 2018, with the gap in 1998 only eighteen wins smaller. 1998 included a Yankee team that made a run at the 1907 Cubs win record, ending with 114. A Braves team at the peak of Maddux/Glavine/Smoltz (Plus Kevin Millwood!) won 106 games and a Marlins team that had just been sold after winning the 1997 World Series lost 104. The early 2000’s Yankees, Braves and A’s drove a small spike between 2000 and 2005, aided by the Lou Pinella Devil Rays. But in recent years, there has been a noticeable dip in polarization. Between 2013 and 2014 the gap between the best and the worst teams shrunk by 38 wins. Since then, the polarization has been slowly increasing, ending with a massive jump of almost 80 wins from 2017 to 2018.

What all of this indicates to me, and something I am interested in looking into further once the season is over, is that the Mariners never really stood a chance this year. We will always have June, but if the true talent level of this team was always closer to .550 and not .600, we never stood a chance at making the playoffs in 2018. There were too many very good teams, in the AL especially, for us to stand a chance and Jerry DiPoto has to figure out if there is enough talent in this organization to reach this higher level of play, or if he should cut his losses and begin to think about the long-term future.

#StatisticalAnalysis