Blue Jays: A 2019-2016 Aaron Sanchez comparison

TORONTO, ONTARIO - JULY 28: Aaron Sanchez #41 of the Toronto Blue Jays reacts during play against the Tampa Bay Rays in the first inning during their MLB game at the Rogers Centre on July 28, 2019 in Toronto, Canada. (Photo by Mark Blinch/Getty Images)
TORONTO, ONTARIO - JULY 28: Aaron Sanchez #41 of the Toronto Blue Jays reacts during play against the Tampa Bay Rays in the first inning during their MLB game at the Rogers Centre on July 28, 2019 in Toronto, Canada. (Photo by Mark Blinch/Getty Images) /

Aaron Sanchez won the 2016 American League Pitching ERA title. He has struggled to attain that level of performance ever since. Was his 2016 as good as it seemed?

Aaron Sanchez was selected 34th in the 2010 MLB June Draft. There were high hopes that he would become a front-of-the-rotation starter. In 2016, he won the American League ERA title; 2016 appeared to be the first of many good seasons for Sanchez.

Caveat emptor

It should be noted that this article is not an analysis of the trade of Sanchez at the July 2019 trade deadline. It is an examination of his 2019 and 2016 seasons.


Recently, Sanchez’s starts as a Blue Jay were better than most of his 2019 outings. As a result, I was curious to see what a Sanchez 2019-2016 comparison would reveal. What I discovered is that many metrics indicate that Sanchez’s 2016 season was fueled by good defense and good fortune. Yes, the dreaded word, luck. Apparently, the 2016 Sanchez of my memory was better than the true 2016 Sanchez.

A 2019-2016 comparison

Unless otherwise stated, the data was sourced from Statcast. With respect to 2019, the data reflects games up to and including July 31. To see the data, click on “Table” in each section that follows.

Sanchez and standard metrics

A summary of some standard stats is found in Table 1 and Table 2.

Observations – Tables 1 and 2

Sanchez’s 2016 ERA and FIP were clearly above average; he was slightly below the mean in terms of K%. 2019 was not as nearly as productive given the relatively poor ERA, FIP, and BB%. The K% deteriorated compared to the average. Sanchez is not a strike-out pitcher and is more dependent upon his defense to get outs compared to a Trevor Bauer.

Table 2 highlights the change in Sanchez’s pitch mix in 2019 compared to 2016.

In 2016, Sanchez was primarily a sinker-ball pitcher. In 2019, his pitch mix is more balanced compared to 2016. The reduction in the use of the sinker since 2016 may be a conscious decision to make lesser use of a pitch that may have contributed to his finger and nail issues.

A deeper stats dive

Tables 3 to 8 cover the following aspects of Sanchez’s 2019 and 2016 performance:

Sanchez and pitch metrics

Tables 3 and 4 presents some Sanchez data by pitch type.

Observations – Tables 3 and 4

  • There is a notable uptick in the xSLG (exit velocity and launch angle) on Sanchez’s sinker since 2016
  • The spin rate of his pitches in 2019 is very similar to their 2016 rates
  • The whiff% of each of his pitches has declined since 2016, particularly for his fastball

Sanchez and pitch movement

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Tables 5 and 6 summarizes Sanchez’s vertical and horizontal pitch movement by pitch type.

Observations – Tables 5 and 6

  • With the exception of his curve, Sanchez’s pitches did not have a lot of vertical movement in 2019 and 2016
  • The lack of drop in his pitches is consistent with his below-average whiff%, which is 21.5% in 2019 and 21.0% in 2016
  • The MLB average whiff% during Sanchez’s career is 24.2%
  • Sanchez’s pitches are above-average in terms of horizontal movement

Sanchez and the batted ball

Table 7 shows how Sanchez ranks in selected metrics.

Observations – Table 7

  • In all cases, the higher the percentile number the better
  • Sanchez’s 2019 fastball has better than average velocity
  • The spin rate on his 2019 curve is elite
  • In 2019 and 2016, the exit velocity and hard hit% on batted pitches was among the worst in MLB
  • In 2016, on batted balls, his expected batting average and expected slugging percentage were middle of the pack
  • Those latter two metrics are relatively worse in 2019
  • A near-average K%, and lower-tier exit velocity and hard hit%, suggests that his 2016 ERA benefited from the play of the Blue Jays defense and/or luck (randomness)
  • According to FanGraphs, the Blue Jays had an above-average defense in 2016 in terms of DRS (#5) and UZR (#11)
  • In 2019, the Blue Jays defense is above-average as measured by DRS (#18) and below-average as determined by UZR (#25)

 Sanchez and recent American League ERA leaders

Table 8 summarizes some metrics of recent American League ERA title winners. For each pitcher, the data presented is for the season in which they won their title. Only the last four ERA leaders were used because Statcast’s data is not available for seasons prior to 2015.

Observations – Table 8

  • The data could be used to form the classic “Which-one-does-not-belong” question
  • With respect to SIERA, Sanchez was in the top-third of starters in his ERA title season
  • Blake Snell, Corey Kluber, and David Price were no worse than 89th percentile in SIERA in their ERA leader seasons
  • In terms of expected results (xSLG, and xBA), Snell and Kluber were 88th percentile or better, Price was 63rd or better
  • Sanchez is the outlier: his expected results in 2016 (xSLG and xBA) were closer to average

Was 2016 really 2019?

The objective of performance evaluation is to use metrics that measure areas for which the player has some control. That is an advantage of using FIP instead of ERA. However, it is good practice to use ERA, FIP, and SIERA in combination to evaluate a pitcher.

Based on the data presented, Sanchez’s 2016 elite ERA metric is inconsistent with the following observations:

  • He was close to the median in terms of xSLG, xBA, and K%
  • His SIERA, which unlike FIP takes into account balls in play, was 32nd percentile, while good it was not elite
  • A higher percentage of his pitches were hit hard compared to the average pitcher
  • The exit velocity on his batted balls was in the bottom-decile

A frequently heard lament has been, “if only Aaron Sanchez could return to his 2016 form”. However, data strongly indicates that 2016 was a bit of a mirage. Yes, his ERA was elite but his pitches were hit hard, which suggests that good defense and good fortune played more of a role in his success than commonly believed.

Sanchez’s BABIP was 0.267 in 2016; it is 0.304 and 0.340 in 2018 and 2019, respectively. The MLB average BABIP during the 2016-2019 seasons is 0.296. Perhaps the relatively low 2016 BABIP is further evidence that Sanchez was the recipient of good fortune in 2016.

Admittedly, we do not know what Sanchez will become in the future. One of the factors to consider is a change in pitching approach. Matthew Boyd, Charlie Morton, and J.A. Happ are examples of pitchers making changes to their approach to great success. Perhaps Sanchez can make noticeable alterations (pitch mix, location, aggressiveness, etc.) and return to his perceived 2016 performance level. Certainly, his six-inning, no-hit performance in his Astro’s debut may be a sign of better days for Sanchez.

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The last word

Aaron Sanchez was once projected as a front-of-the-rotation starter. Given the illusory success of 2016, he now looks like an average starter, at best. He may find more success as a bullpen arm given his above-average fastball velocity and a top-tier curveball. For starting pitcher Sanchez, many non-ERA metrics tell us more about what should have happened in 2016 rather than what 2016’s ERA can inform us about his future as a starter.