What Is a Bullpen in Baseball? And Why You Need a Good One


A fan films a Los Angeles Dodgers pitcher throwing in the bullpen with their phone.

Nearly every time you watch a baseball game these days, you will see this scene at least once:

A pitcher is on the mound, struggling, and clearly on his last leg for the night. The manager emerges from the dugout and gestures somewhere off in the distance towards the outfield. A new pitcher emerges from the bullpen.

So what is a bullpen in baseball?

A bullpen is a term used to describe a group of relief pitchers as a whole, whose job is to replace starting pitchers and finish games. The term also describes the physical area, which is usually enclosed and beyond the outfield walls, where relievers sit and warm up before entering games.

The bullpen is an integral part of baseball that has only grown year after year in importance as the roles of pitchers have changed over the last few decades – in particular relief pitchers. We’ll look into the role the bullpen plays, how that’s changed over time, and what roles different pitchers in the bullpen serve.

Why Is it Called a Bullpen in Baseball?

Three baseballs sitting along concrete steps.

There are many terms that are mostly unique to baseball, and “bullpen” is certainly one of them. Of course, it is also used in a more literal sense in rodeo, which seems to lend credence to the theory that the two are related.

There is no clear reason why it is called a “bullpen”, but one theory is that a baseball bullpen is similar to pens at rodeos, where bulls are held in reserve in case the primary bulls are unable to go. Another theory involves Bull Durham tobacco signs that were prevalent in many early-1900’s parks.

On the surface, the first theory seems to make the most sense, given the similarities between a baseball and rodeo bullpen—both are enclosed areas away from the action that hold reserves that are ready in case the primary performer cannot do their job.

However, the Bull Durham theory seems to be the primary driver behind the term becoming popular in the early 20th century.

This theory states that the term was popularized because signs for Bull Durham tobacco were prevalent in many baseball parks in the first decade of the 20th century and were often located on the outfield fence near areas where pitchers warmed up.

By 1915, the term “bullpen” was definitely used as a term describing the area where pitchers warmed up. However, that was probably influenced by a term used in baseball for nearly four decades before then, albeit in a very different way.

As early as 1877, the Cincinnati Enquirer referred to a roped-off area in foul territory as a “bullpen.”

This area, which was on the field of play, actually was used as a standing-room area for late-arriving fans, borrowing a term that at the time was often used to describe a holding cell or jail.

As the concept of relief pitchers was still decades away, it would be a while before the term truly applied to an area for pitching.

However, considering that in most early ballparks, relief pitchers would warm up in foul territory (usually down near the foul poles), the term’s meaning eventually changed.

Fans are no longer allowed to stand in roped-off areas on the field, and relievers are confined to their defined area, leaving no doubt what exactly the bullpen is today.

What Is a Relief Pitcher in Baseball?

In baseball, pitchers can be split into two general categories: starting pitchers and relief pitchers. These two roles are related, though their roles contrast significantly.

A relief pitcher is a pitcher whose job is to replace, or “relieve” a starting pitcher, usually because a starter is either tired or ineffective. These pitchers often pitch in short stints, often an inning or less, and are deployed frequently toward the end of games.

While starters are usually designed to pitch several innings (usually 5-7), relievers are used much differently, as their roles are often clearly defined and don’t pitch more than one inning.

As a result, relievers are often referred to as “max-effort” pitchers who expend energy rapidly, rather than pacing themselves like a starting pitcher would over several innings.

Most Major League Baseball teams employ seven or eight relief pitchers (in addition to five starters) at any given time, most of whom have roles and points in the game that they typically work.

What Roles Do Relief Pitchers Hold?

Baseball pitcher throws a pitch home.

As stated, relievers are in charge of finishing out games. Depending on how the rest of the game plays out, what that looks like can vary drastically. Regardless, as we said earlier, pitchers coming out of the bullpen usually have roles that are more-or-less defined.

Relief pitchers have roles that range in leverage, from long and middle relievers working lower-leverage scenarios to set-up men working in high-leverage situations, and finally, closers whose main job is to finish games.

In most bullpens, teams employ several middle relievers who tend to work in the middle (5th-6th) innings of games when starters have shorter outings. These pitchers are often less effective, which is why they work in a part of the game with lower leverage.

After middle relievers, teams usually have one or two “set-up” relievers who work the 7th and/or 8th innings, with the intent of holding a lead for the closer, who is often the best reliever on the team.

The closer usually only works the 9th inning, and often only pitches with a small lead or if the game is tied. He may occasionally enter the game a little earlier as well.

Bullpens are also usually filled with one or two long relievers. These pitchers are often converted starters who work multiple innings in case a starting pitcher exits a game early, or if a game goes to extra innings.

They often are the least effective pitchers in the bullpen and usually work in low-pressure situations.

As a whole, the bullpen carries an integral role in baseball, especially in the 21st century. When the term “bullpen” was first coined in the 19th century, over 90% of pitcher starts were complete games, so reliever use was rare.

Even by World War I, when the term was first used to refer to relief pitchers, 55% of games were completed by starting pitchers.

However, in 2019, less than one percent of starts were complete games, meaning that virtually every single major league game involved the bullpen in some capacity.

As a result, a strong bullpen was more critical to success than ever. This was the case in 2019, as 8 of the 10 playoff teams had a bullpen ERA in the top-11 in the majors.

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Steven G.

My name is Steven and I love everything sports! I created this website to share my passion with all of you. Enjoy!

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