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Ranking the top rotations for 2019

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In order to rank the pitching rotations for the newly started 2019 season, I first needed to look back on the year before. Thanks to the wonderful website of FanGraphs, I was able to easily sort data and look at team’s starting pitcher statistics from the 2018 season. Seen below is a chart ranking the team’s starting pitchers results sorted by FIP. I had wanted to use xFIP for this experiment however due to calculations that I would need to do later on, I wouldn’t be able to use xFIP.

Data via Fangraphs

When I first took a look, I was surprised at a few teams that landed towards the top. The Diamondbacks, Rays, and Phillies are all teams that don’t come to mind as to having one of the best rotations in baseball. All of those teams do have a handful of good pitchers and even the Rays and Phillies each have their own superstar, but I still didn’t expect them to rank that high. Regardless, this is a good place to start to rank the top pitching staffs for the 2019 season.

I also exported individual player data from FanGraphs and organized it by teams. I exported only starting pitchers who had more than 50 innings pitched. From there, I narrowed each rotation down to five pitchers to form a teams rotation. I decided to calculate the FIP of the five starters who had the most innings or games started last season. I used both to consider which players had the biggest impact on the rotation. I recorded my results below in the first numeric column and next to it on the far right is the team’s FIP for all of their starting pitchers. That column is obviously a more accurate representation of their rotation’s performance, however, for this experiment, it’s best that I use the calculation for the team’s five most significant starters. So, you can see below the data collected from the experiment along with the actual FIP for each team in baseball.

Data from FanGraphs

Upon completion, I decided to correlate the two columns to make sure that there isn’t a huge difference in calculations. I was also curious as to how much of a difference there would be. I figured that teams who had a large difference between the two would be an indication that those teams used many different pitchers throughout the season. I made this conclusion because teams who have five consistent starters throughout the entire season would be the exact same as the actual FIP from starters. The reason behind the use of many different pitchers could include many variables like injury or lack of effectiveness.

Calculated on Social Science Statistics
r=0.8783

After running the correlation, I was able to see that there was not that much of a significant difference between the two calculations. The X-Values is attached to the calculated FIP while the Y-Values are attached to the actual FIP from starters. The correlation doesn’t indicate that large of a difference as you can see from the graph and also that r=0.8783.

Now that the baseline is set, I need to adjust the rotations for the 2019 season. The first part of that is making the adjustments from trades and free agent signing. In order to do so, I looked at the depth charts on MLB.com and on ESPN. I then changed the composition of each rotation to align with the MLB depth charts for the 2019 season. Now, with the updated rotations and each team’s FIP calculated, I had reached the point that I was ready to apply a regression experiment.

I applied a regression toward the mean (ATM) algorithm to each pitcher to predict their performance for the 2019 season. I calculated regression for each variable in FIP including home runs, walks, hit by pitches, and strikeouts. Accordingly, each regression was applied to every player projected to be in a rotation for every team in major league baseball. In the final step, I calculated each team’s FIP based upon the five starting pitchers projections for the 2019 season. The final results can be seen below for my rankings of rotations in Major League Baseball for the 2019 season.

When I started the experiment, the Astros were a team that I didn’t expect to finish in first place. With the loss of Lance McCullers Jr. for the season, Charlie Morton to free agency, and the almost definite loss of Dallas Keuchel, the back end of their rotation may not look as promising as it had in the past few years. However, their projected FIP was still enough to place them in the top spot, just barely above the Indian’s rotation. It was so close between the two only 0.006 separated them. Wade Miley was an offseason acquisition by the Houston Astros in their attempt to make up for lost pitching. He may be next in line to be transformed into a superb pitcher by the Astro’s organization just like they have done in the past. Their most recent success story was Charlie Morton who ended up playing a big role in their 2017 championship season. The Astro’s rotation may have taken a hit this offseason, but it still remains at the top.

I was shocked when I first saw that the Yankees didn’t finish as high as expected. The already elite rotation added James Paxton this offseason making them one of the best in baseball, or at least that’s what I had thought. Finishing in tenth place was not where I had expected them to fall, especially behind the Cardinals and Phillies. However, with each of those teams possessing young talent that is starting to blossom, it seems as this was bound to happen eventually. This ranking may come as a surprise to fans now, but it may be something that people can’t believe they didn’t foresee after this season.

It turns out, that the low ranked Yankees was just the beginning of the surprises embedded in the data. Coming in at 21st overall is the Chicago Cubs rotation. I definitely didn’t see that coming, to say the least. A rotation that includes Jon Lester, Kyle Hendricks, Jose Quintana, Yu Darvish and Cole Hamels (listed in no particular order) is one that you may think is one of the best in baseball. However, now it seems that the majority of the group may be past their prime no matter how big the names are in that rotation. Similar to the Yankees scenario, it may be a surprise now, but after the season, could appear to have been so obvious all along.

In 2019, pitching will continue to have the upper hand as in recent years and hopefully I provided you with insight as to who will lead the pack. These rankings could change throughout the year from either injury or trade but for now, these are the best of the best. The 2019 season is now underway with two games played in Japan last week so it’s time for these rankings to be put to the test. Let’s see if the Astros really do have the best rotation in baseball or if the Yankee’s rotation may be a little overrated. Not to mention the Cub’s rotation ending up as insignificant and past its prime this season. The 2019 season will answer these questions and lucky for us, it’s here.

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