Meaning of MRP and LRP in Baseball Explained

Michael Claunch

Acronyms have infiltrated baseball over the last 20 years. Terms regularly used by players, coaches, and fans have been shortened, with many people now only knowing them by two or three letters.  

Two commonly used terms in baseball are LRP and MRP. You might be thinking, what do LRP and MRP mean in baseball? Well, the answer is simple, as both acronyms refer to pitching.  

Don’t worry; neither of these terms refers to analytics and stats, which many baseball fans are tired of hearing about. Rather than stats, LRP and MRP describe the type of pitcher a baseball club may utilize. 

Both pitchers are key members of any big-league ball club, and a World Series could be won thanks to a team’s LRP or MRP.  

What does LRP mean in baseball? 

The bullpen is where you will find an individual capable of being an LRP. The acronym means long relief pitcher and expands on the old baseball term relief pitcher.  

There was a time when all non-starting pitchers were relief pitchers. Yet, the evolution of the game has forced managers to create different types of relief pitchers. 

The long relief pitcher is often called upon to replace a starting pitcher. It is the LRP’s job to take over if a starter has been knocked out of a game early. Oftentimes, the long relief pitcher will need to soak up innings to prevent the other arms in the bullpen from being used up.  

So, what does LRP mean in baseball in terms of distance or number of innings? A baseball manager will use a long relief pitcher over the course of multiple innings. Most long relief pitchers are ex-starters, which makes them capable of going for multiple innings at a time.  

However, LRPs can bounce back quickly due to throwing fewer innings rather than a full game. Perhaps, in certain situations, an LRP can come back the following day or the day after.  

A long relief pitcher may also be used as a “spot starter”. The spot starter is a pitcher that is used in certain instances to give a member of the five-man starting rotation an extra day of rest or if a starter is skipped over in the rotation. 

What does MRP mean in baseball? 

MRP is another type of pitcher. While LRP means long relief pitcher, MRP is the middle relief pitcher. Both players are similar in that they are used to replace the starting pitcher of a game. However, unlike an LRP, the middle relief pitcher isn’t used for long outings.  

The MRP will throw one inning, two at the most. Oftentimes, a baseball manager will call upon an MRP hurler to throw the fifth, sixth, or seventh innings of a game. The middle relief pitcher is a stop-gap to get from the starter to the set-up man.  

In some cases, the MRP may be used in a specific situation to face a certain batter. A tactical switch could be pulled by a manager to bring on an MRP due to being left-handed or right-handed, thus forcing the batting team to alter its tactics. 

“Baseball” by PMillera4 is licensed under CC BY-NC-ND 2.0. To view a copy of this license, visit

A middle relief pitcher will come on for the starting pitcher in most situations. Before the use of the designated hitter (DH, another acronym!) in both the American and National Leagues, a pinch hitter would replace a starting pitcher. This would allow the MRP to be deployed.  

Modern baseball sees MRPs often given away to setup (SU) pitchers in the eighth inning. A closer (C) would then be used in the ninth to hold onto a lead.

Why use an LRP and MRP pitcher? 

There are different reasons and situations for using an LRP and MRP pitcher during a baseball game. The most obvious reason is due to a starting pitcher having a poor outing. A manager may need to call on an LRP to eat up innings and try to get the game under control. An LRP pitcher is perfect for taking up multiple innings.  

An early blowout would also see an LRP pitcher used. Once again, the pitcher is eating up innings and preserving the arms of the starting pitchers or other members of the bullpen. A long relief pitcher can conserve the energy of the other pitchers on the staff.  

An MRP hurler is ideal for the role of bullpen fireman. The fireman was used to stop a rally or to extinguish a team from catching fire and making a comeback. An MRP could be brought on anytime a rally begins, and it is his job to douse the fire before it becomes a blaze.  

In addition, both the LRP and MRP are now specialized baseball pitching roles. A big-league team may carry as many as eight relief pitchers. Each has his role to play. Depending on how a manager wants to deploy his staff, he could designate each pitcher to a specific role to help the team win games. This should clear up some of the confusion around the question of what LRP and MRP mean in baseball.

Why do baseball teams use relief pitchers? 

Long ago, baseball teams rarely used relief pitchers. The same pitcher would throw an entire game and sometimes come back the following day to pitch once more.  

The evolution of the game altered the way pitchers are used, and managers began to realize that greater success could be obtained by changing hurlers during games. It wasn’t until the 1970s that baseball bullpens started becoming more specialized. 

Before the 1970s, starters were expected to pitch all nine innings and only come off the mound if they had a truly bad day out. Therefore, relievers were considered pitchers no longer able to start games. 

In the 1990s, teams began to focus on using closers to finish out games and hold leads. The use of closing pitchers also forced a rethink of the long relief and middle relief pitchers.  

So, what do LRP and MRP mean in baseball? The LRP is the long relief pitcher, while the MRP hurler is the middle relief man. Both fill the gap between the starter and the set-up pitcher during a game. While the LRP eats up innings and goes multiple frames, the MRP is typically on the hill for one inning.  

Leave a Comment