In The Lab: Pitching Rotation and Bullpen Breakdown

My appreciation for statistical analysis stems from two major factors. There are two prominent cognitive biases that this practice helps counter, both of which affect all of us at some point. The first of these is what I refer to as recency bias. A perfect illustration of this is the sequence of brief outings by starting pitchers that the Astros are currently enduring. It is easy to fall into the trap of believing this has been a constant issue throughout the entire campaign, though that is rarely true. These trends naturally fluctuate, meaning that analyzing cumulative statistics serves as an effective countermeasure to this mental shortcut.

The second cognitive shortcut is regional bias. Our focus is primarily on the Astros, with many of us following their games with absolute devotion. Consequently, when we observe a single franchise 162 times in a year while only catching glimpses of other clubs occasionally, we tend to evaluate our local team’s performance in isolation and conclude it is exceptionally superior or inferior. We simply lack a broader point of reference. This issue becomes critical when analyzing a squad’s comparative advantages and shortcomings, directly influencing both immediate in-game tactics and overarching roster assembly decisions.

This segment is dubbed the laboratory because I prefer to begin with concrete observations that can be formulated into a verifiable theory. Here, our premise is that the Astros depend too heavily on their bullpen to record outs because their starting rotation fails to pitch deep into games. We can easily verify this assertion by measuring their performance against the rest of the American League. To begin our analysis, we will examine only the starting rotations, focusing on their total innings completed and their collective earned run average.

It is worth pointing out that the most striking takeaway is not merely that Houston ranks fourteenth in starter ERA, but rather the massive gap separating them from the thirteenth-place Twins. To borrow an expression from my grandfather, they are buried so deep in the basement that they need to pipe in daylight. Indeed, if we factored in home-field environments to adjust these metrics, a strong case could be made that the Astros’ starting staff has actually been the least effective in the entire American League this year.

Unsurprisingly, they find themselves in thirteenth place regarding starter workload. While the extremely low total for the White Sox is quite shocking, the rest of the league falls into a more predictable distribution. Three franchises sit within fifteen innings of the Astros’ season total. Across a stretch of 120 contests, a fifteen-inning margin is relatively minor. These statistics ultimately address our primary inquiry: are our initial perceptions accurate? The short answer is yes. This pitching staff does not go as deep into matchups as the vast majority of its peers. While these cumulative figures do account for the highly problematic opening months, the overall picture reveals a starting staff that has performed well below average.

Naturally, additional context is required before determining whether this limited starter volume is beneficial or detrimental. While most observers would immediately assume it is a negative trait, I urge caution before arriving at that verdict. Looking back at the history of the sport, bullpen preventatives routinely yield better collective ERAs than their starting counterparts. Consequently, a positive variance is to be expected. To illustrate how this dynamic plays out across the league, I will present the performance gap between starting units and relief corps.

A well-known adage suggests there are lies, damned lies, and statistics, but that represents a major oversimplification. Data points are immutable, and nothing can alter their reality. The true variable lies in our translation of those figures. The fact remains that the Astros occupy the third spot in bullpen workload. That is an indisputable reality. The real discussion centers on how we choose to interpret this reality.

Traditional baseball philosophy dictates that heavy reliance on a bullpen is a negative indicator. This is the point where traditionalists typically reminisce about an era when starters routinely finished what they started, back when players were rugged and expectations were different. I would propose an alternative perspective. My view is simply that a team should maximize the usage of its most productive assets as much as possible. Consequently, every skipper faces a unique challenge. Managers overseeing a negative differential have relievers who perform worse than their starters, meaning they should ride their rotation as long as possible. Conversely, clubs experiencing a positive differential ought to lean heavily on their bullpen.

The most effective leaders are those capable of tailoring their strategies to their roster’s actual performance. The Astros possess the widest margin in the American League, and likely in all of Major League Baseball. Though it may run contrary to traditional thinking, they should probably embrace this approach even further, much as they have done recently. Granted, concerns about fatigue and workload limits cannot be disregarded, but as a basic premise, the relief unit represents the strongest segment of their pitching staff—a reality that has become even more pronounced since the start of May.

Naturally, this dynamic carries significant consequences for roster construction. The peculiar aspect of this pitching staff is the presence of several arms who excel out of the bullpen but struggle when tasked with starting. This category features pitchers like Tatsuya Imai, Cristian Javier, and Kei-wei Teng. Conversely, another segment of the staff has handled heavier workloads in multi-inning relief roles. While it presents a puzzle for any coaching staff, this club might actually benefit from limiting their starters to four or five innings and letting the bullpen handle the heavy lifting. Although they risk exhausting their relievers down the stretch, the alternative is running out the least productive rotation in the American League and simply hoping for a miracle.