Blue Jays: Roberto Osuna and the season of streaks

Roberto Osuna has been an enigma during the 2017 season. He had a remarkable streak of successfully closing 22 straight save opportunities between April 29 and July 17; subsequently, Osuna has blown 7 of 18 save opportunities and may set the Blue Jays single-season record for blown saves.

An important caveat to note is that with Roberto Osuna we are dealing with a small sample size. During the entirety of his career, Osuna has pitched just over 200 innings, the equivalent of one Mark Buehrle season.

Accordingly, the purpose of this article is not to provide answers as to why Osuna is struggling. My objective is to provide a list of key performance data for easy reference and then posit some questions that flow from the numbers.

Brooks Baseball Data

What are the key observations from the Brooks Baseball data?

• During Osuna’s recent struggles, his use of the fastball has declined significantly compared to 2016;
• Osuna has employed the cutter considerably more during the same period;
• Since 2016, the velocity of the fastball and slider has slowed noticeably;
• The horizontal movement on the fastball has decreased from its 2016 level;
• As 2017 has unfolded, the cutter is breaking more towards Osuna’s glove side than it did in 2016; and
• The slugging percentage against the fastball (0.424 for all of 2017 to date) has increased since 2016.

FanGraphs Data

What are the key observations from the FanGraphs data?

During the April 29 to July 17 streak, Osuna’s strikeout rate was elevated and the hard contact was down;

The ground ball rate has steadily increased since 2016 and the fly ball rate has decreased;

BABIP was very low during the good streak and very high during the bad run; and

Osuna’s ERA was bloated in the latter half of 2017 and miniscule during the period of no blown saves.

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There are many questions to ask

As noted, we are dealing with a small sample size in the case of Roberto Osuna. Accordingly, there are no conclusions to draw at this time but there are many questions to ask:

• What is the cause of the reduced pitch velocity?
• Why is there less horizontal movement on the fastball but more on the cutter?
• How much of the recent troubles can be attributed to bad luck? Certainly a 0.377 BABIP indicates bad luck but the reduced pitch velocity and horizontal movement on the fastball, as well as the decline in soft contact, suggests that it is now easier to get base hits off Osuna;
• According to FanGraphs, the Blue Jays rank 26^th and 23^rd in terms of Defensive Runs Saved and UZR/150, respectively. In 2016, the Blue Jays were top 10 in both metrics. Has the decline in defensive prowess, together with a higher ground ball rate, contributed to a higher BABIP?
• What impact has Osuna’s publicized anxiety issues had on his performance?
• Many people have observed that Osuna has lost weight during the 2017 season. Has the weight loss affected his pitching?

The Last Word

Hopefully, I accomplished what I set out to do from the outset: provide key performance data from Roberto Osuna’s up and down season and then pose questions that flow from the data. Perhaps you, the reader, can use the Comments section to suggest additional questions. Also, are there readers brave enough to offer opinions as to the cause of Osuna’s recent poor performance? If the answer is yes, please consider the following words of wisdom:

“Economists don’t forecast because they know, they forecast because they’re asked”

John Kenneth Galbraith

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