Evaluating 2020 Strength of Schedules

Normally, strength of schedule is not a factor we need to heavily consider in fantasy baseball analysis. Because each team plays their entire league, as well as a few interleague opponents over the course of a 162-game season, there is little, if any, advantage to be gained from the quality of the teams on your schedule. However, and you’re probably used to hearing this, 2020 was different.

 

Separate by Divisions

 

This past MLB season essentially consisted of three separate leagues. If you were in the NL East, all of your opponents were either a divisional rival or a team from the AL East. The same goes for teams in the Central and West. Naturally, this abnormality produced three separate run-scoring environments.

The East contained the most offense of the three division groups in 2020 by a wide margin. Another factor we need to consider is the calculation of league adjusted stats, such as wRC+. Traditionally, wRC+ adjusts for the league average wRC/PA, whether it is the American League or National League. Usually, that makes sense; 142 of each team’s 162 games are played against opponents from the same league.

However, in 2020, league adjustments are not appropriate. Why should we compare Jose Abreu and Anthony Rendon on the same scale when they faced zero common opponents? Shouldn’t we measure how each hitter performed relative to their division rather than their league?

To fix this, I calculated the average wRC/PA for each of the three divisional regions and used it as the denominator for each player’s wRC+, rather than “AL or NL wRC/PA.” Let’s call this new calculation “true wRC+.” Here’s a look at how the top ten qualified hitters in baseball from 2020 changed:

As you may notice right away, five of the six best hitters in terms of wRC+ were from the AL or NL East, the highest run-scoring environment. On the other hand, Jose Abreu, Nelson Cruz, and Jose Ramirez see major boosts from facing competition with better pitching.

Similarly, for FIP-, an adjusted pitching metric, the denominator is league-specific FIP. Using the same process as wRC+, I took the average FIP for each division as the denominator. Here are the results:

We see a similar trend here. Since the East contained more offense, we see an upgrade to Jacob deGrom’s numbers. This is significant because both Cy Young winners came from the Central division, the lowest run-scoring environment. It’s hard to make an argument against Shane Bieber in the American League, but perhaps competition level could have given the edge to deGrom over Trevor Bauer in a very close NL Cy Young race.

 

Adjusting for Schedule

 

In addition to accounting for run environment, we need to look at players’ specific schedules in our fantasy analysis for 2021. A starting pitcher in a traditional five-man rotation would have made just 12 starts in 2020.

Depending on how the schedule shaped up, a certain pitcher could have faced a group of disproportionally great offenses, hurting his overall numbers. Of the 40 qualified starting pitchers in 2020, here are the three who faced the easiest and most difficult opponents in terms of average team wOBA.

Naturally, the three pitchers who faced the most difficult schedules in 2020 all came from the East, and two from the same team.  For reference, the opponents of the starting pitcher with the toughest schedule in 2019 (Charlie Morton) averaged a 0.324 wOBA whereas the pitcher with the easiest schedule (Julio Teheran) faced teams who averaged a 0.313 wOBA.  In normal seasons, the difference between an easy and difficult schedule is not very drastic.

Therefore, 2020 is the only season where we need to account for strength of schedule in our analysis.

It is important to take note of how much this can impact certain pitchers. Patrick Corbin had a down year in 2020, relative to his standards. His FIP, xFIP, and SIERA were all above 4.00 for the first time in four years. Because he faced the second-toughest schedule of any starting pitcher, it may be fair not to be overly concerned about one of the better pitchers in baseball.

Due to smaller sample size, relievers produce even more dramatic results.

Once again, we see the toughest schedules come from the East whereas the easiest come from the Central. In fact, the three players with the lowest average opponents’ wOBA all played for the Cincinnati Reds. As you may notice, the range of strength of schedules is slightly wider for relievers than for starters.

If you are using 2020 statistics to make projections for 2021, it is clear that you need to make some sort of schedule adjustment. Opponent-adjusted statistics are frequently seen in sports like football and college basketball, where fewer games are played and each team’s schedule is drastically different from one another.

This is typically not necessary in baseball because the season is long and each team plays at least seven games against every opponent in their respective league.

However, as we have proven, 2020 is a different story. We need to adjust each player’s stat line based on their schedule relative to the league average. Let’s use Zack Wheeler as an example. Wheeler posted a 3.22 FIP in 2020.

He faced opponents who averaged a 0.337 wOBA, which is about 5.3% above the league average wOBA (0.320). The league average FIP was 4.45. 5.3% of that would be about 0.24, so we will adjust Wheeler’s FIP down by 0.24 points, giving him an adjusted FIP of 2.98. Look how this applies to the other members of the leaguewide leaderboard.

Unlike many of the other previous lists, the three divisional regions are relatively balanced here.  Surprisingly, the adjusted FIP leader from 2020 was actually Jacob deGrom rather than Shane Bieber.

As I mentioned, Wheeler gets a massive positive adjustment, in addition to Aaron Nola and Hyun Jin Ryu due to facing strong offensive teams. On the other hand, Bieber and Yu Darvish are penalized for facing a weaker schedule.

Using the same concept, we can determine a leaderboard for adjusted xFIP and SIERA as well.

Clearly, if the voters had factored in the quality of opponents, they would have given deGrom much more consideration for his third consecutive NL Cy Young instead of Bauer.

Hyun-Jin Ryu is a player I am high on relative to consensus because of his strength of schedule in 2020. A third of his starts came against the Yankees, Mets, or Braves, three of the four best offenses in 2020. While he will obviously be pitching in the AL East again in 2021, it will be balanced out by starts against weaker hitters in the Central and West.

On the other hand, I have no interest in Luis Castillo at his current ADP as the #10 starting pitcher. Castillo gave up four runs, two walks, and six hits with four strikeouts in four innings pitched in his first start of the year against the Twins.

After that, he did not face a single team with a wRC+ above 100 for the rest of the year. Consequently, Castillo’s adjusted numbers take a massive hit because of the weaker competition.

 

Overperformers and Underperformers

 

 

Here, we can see who underperformed and overperformed their ERA the most, based on adjusted SIERA. Matthew Boyd actually faced a relatively easy schedule coming out of the AL Central, but his ERA was so flukily high that he still gets the top spot on this list.

Kyle Gibson’s 4.81 adjusted SIERA puts him more in line with his career numbers, making him a potential buy late in fantasy drafts.

On the other side of the coin, we have even more of a reason to put the brakes on Trevor Bauer’s elite season. Relative to his schedule and peripherals, Bauer was a massive overperformer in 2020.

Considering he is currently being drafted as the number four starting pitcher and will potentially face a tougher schedule with a new team, I will be drafting very little, if any, shares of him.

Dallas Keuchel is another major fade for me in 2021. While Keuchel has been known to overperform his peripherals throughout most of his career, I would be shocked to see him repeat his 2020 success.

Additionally, like many other Central pitchers, he got dealt a relatively manageable hand with his schedule. Aside from the White Sox, who Keuchel obviously did not face, there is not a single team from the Central who was among the top-15 offenses by wRC+ in 2020.

 

Summing it All Up

 

These are just the basics of schedule-adjusted analysis. You can do the same thing with hitters or perform more advanced adjustments to get a better idea of what to expect for 2021.

The main theme here is that we should be considering pitchers who faced tough competition in the offense-heavy East while fading pitchers from the Central. For hitters, players from the Central likely faced disproportionally tough pitchers and may have underperformed their true skillset.

Hopefully, 2020 will be the last shortened season we have to worry about. But for this year, it’s important to take note of the competition certain players faced as we prepare for our fantasy drafts.

Photos by Cliff Welch/Mark Goldman, Icon Sportswires | Adapted by Jacob Roy (@jmrgraphics3 on IG)