Blue Jays Key to Success #4 – Better Starting Pitching Depth

The Blue Jays used nine starting pitchers outside of their Top 5 and they did not collectively pitch well. Better performance from the non-Top 5 starters could be key to the Blue Jays in 2018.

This article is the fourth in a series about areas in which the Jays need to improve to contend in 2018. The first article was about beating the bad teams, the second was about winning in April, and the third concerned Roberto Osuna.  The focus is not on large targets – like staying healthy, or scoring more runs than the other guys – but rather on smaller areas where the Jays have underperformed in recent years and where improvement could translate into those critical few additional wins.

Injuries to the 2017 Blue Jays starting pitchers certainly diminished their optimal performance level. Most noteworthy was Aaron Sanchez‘s lingering blister problem. Although I believe that the impact of the 2017 injuries was overstated by many, in part because all teams suffer from them, the injuries did create challenges for the team.

All data is courtesy of FanGraphs.

The Blue Jays used seven starting pitchers in 2016 and 14 in 2017. On average, each American League team used 11.6, 10.2, and 10.3 starters in 2017, 2016, and 2015, respectively.  Let’s assume that a team’s best starters are their Top 5. Accordingly, optimal performance will not be achieved if more non-Top 5 starting pitchers are used, and used often.

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The importance of quality depth

A team can influence the likelihood of injuries occurring through sports science and other means. However, they cannot eliminate injuries; what they can do is mitigate the impact of injuries. This is accomplished by having, on a relative basis, better quality depth from which to draw upon when injuries happen. We see that is what the Blue Jays did this off-season by acquiring Aledmys Diaz, Yangervis Solarte, and  Gift Ngoepe. The position player depth of the 2018 Blue Jays looks better than it did in 2017. We will see later in the article that the Blue Jays did not have adequate starting pitching depth in 2017.

For this article, I sorted the American League starting pitcher data by starts, from most to least. I then separated the sorted data into 2 pools: top 75  and the rest. I then calculated the ERA of the rest. (Note that 75 is the product of 15 AL teams multiplied by 5 starters per team).

How did the 2017 Blue Jays non-Top 5 starting pitchers measure up?

Note that the average number of starts for all starting pitchers do not sum to 32.4 due to rounding.  (32.4 is the result obtained by dividing 162 games by 5 starters).

What was the 2017 impact of starting pitching injuries on performance?

The calculations that follow, for the sake of simplicity, exclude any effect on the bullpen. Furthermore, any impact is measured relative to league averages.

Starting pitching injuries had a direct and an indirect effect upon the Blue Jays 2017 performance. First, the direct impact was the increased innings relative to the average team’s innings percentage split between Top 5 and non-Top 5 starting pitchers. Second, injuries necessitated using non-Top 5 pitchers. Accordingly, the indirect effect was the relative performance of the Blue Jays non-Top 5, compared to the related American League average. These two effects are quantified using earned runs and the related impact on wins.

The Blue Jays non-Top 5 starting pitchers gave up 141 earned runs in 2017; the Top 5 starters gave up 300.

According to FanGraphs, every 10-run improvement in run differential would have produced an additional win in 2017.

The impact of above-average innings for the non-Top 5 starting pitchers

The innings pitched by the 2017 non-Top 5 Blue Jays starters was 5.3 percentage points higher than the AL average. Specifically, 25.0% less 19.7%. Accordingly, the non-Top 5 starters pitched 46 more innings on this basis [868 x (0.25 – 0.197)].  The impact of the above-average number of innings is calculated as the difference in Blue Jays non-Top 5 and Top 5 ERA, divided by 9, and then multiplied by the 46 innings or [(5.84 – 4.15)/9 x 46]. In other words, transferring innings to the starters with the lower ERA will result in a reduction in runs allowed. Therefore, the Blue Jays run differential would have increased by 8.6 runs (0.86 wins) with the average percentage split between Top 5 and non-Top 5 innings.

The Impact of poor non-Top 5 performance

The ERA of the Blue Jays non-Top 5 was 0.58 percentage points higher than the AL average for non-Top 5 starters (5.84 less 5.26). The performance impact is the difference in Blue Jays non-Top 5 ERA from the related league average ERA, divided by 9, and then multiplied by the average number of innings. The average number of innings is 868 multiplied by 19.7%, or 171. Therefore, the impact of below-average performance was 11.0 runs [(5.84 – 5.26)/9 x 171]. Hence, had the 2017 Blue Jays non-Top 5 starting pitchers produced the AL average ERA of non-Top 5 starters, the Blue Jays run differential would have increased by 11.0 runs (1.1 wins).

What does it mean?

The 2015-2017 average number of innings pitched by American League starting pitchers per season is 913. Over the same period, the average number of innings pitched by non-Top 5 starters is 162. Their ERA is 5.29. Let’s assume that those figures, 162 and 5.29, are the 2018 league numbers.

If the 2018 Blue Jays non-Top 5 starting pitchers could generate an ERA that is 0.50 less than the noted 5.29 average, that would increase their run differential by nine or 0.9 wins [(5.29-4.79)/9 x 162]. If the ERA is one percentage point lower, the run differential would be 18, or 1.8 wins [(5.29-4.29)/9 x 162]. That is not an insignificant number given that the wildcard race is expected to be close.

Starting pitching depth is key

The 2017 season demonstrated that a team can partly meet the challenge of injuries through better depth (see the Dodgers). Unfortunately, the 2017 non-Top 5 Blue Jays starters included the likes of Matt Latos, Mike Bolsinger, Casey Lawrence, Nick Tepesch, and Cesar Valdez. Of the non-Top 5 group, three starters combined for almost 68% of the innings pitched. Alas,  the ERA of this sub-group was 5.57, or 0.31 percentage points higher than the average.

For this upcoming season, the Blue Jays will be able to draw upon the talents of Ryan Borucki, Thomas Pannone, possibly an improved Joe Biagini, and others. On paper, the 2018 pool of non-Top 5 starters currently looks better than the 2017 collection.

Next: Pressure to perform due to new found depth

The last word

In 2017, J.A. Happ spent 43 days on the disabled list and Sanchez only pitched 36 innings. Obviously, the fortunes of the Blue Jays would be enhanced if their starters spent less time on the disabled list. However, better relative performance from the non-Top 5 pitchers could be key to the success of the 2018 Blue Jays.