1900s to 1960s: Early History

During the infancy of the National League, both teams struggled out of the gate.^[13][14] The Pirates saw most of their roster decimated as most had defected to the Players' League. Pittsburgh would manage brief periods of success headed into the new century; including three straight NL Pennants from 1901 to 1903 and a World Series victory in 1909.

Cincinnati fared much worse, failing to qualify for the postseason every season until 1919. Even then, the team arguably only won the 1919 World Series against the heavily-favorited Chicago White Sox because of the Black Sox Scandal. While the Reds weren't involved in the scandal, it tainted the legitimacy of their first World Series championship.

The Pirates managed to stay competitive, culminating in another World Series title in 1925. Both clubs managed levels of success at various times, though they often avoided one another heading into the postseason. The Reds finally managed their own turn of success with a World Series victory in 1940 (their first championship earned outright) whilst the Pirates were in the midst of a playoff drought for nearly two decades. Though, by the end of the 1950s, the Pirates briefly returned to success with another World Series victory in 1960, the Reds managed to win the pennant the following season; narrowly beating out the divisional rival Los Angeles Dodgers in the process, though the Yankees prevailed to win the Championship in five games. Both teams would soon spend the duration of the 1960s in a rebuild; however, by the turn of the decade, the competition quickly heated up.

1970s: Fierce NLCS Matchups

1980s regression

The Pirates and Reds both saw a sharp regression from their heyday in the 1970s, ironically for the Reds, they finished with the league's best record in 1981 but headed into the all star break before a player strike suspended the season.^[19] The Reds would fail to make the postseason as a result of the losses to the roster. The Pirates had sunken deep into mediocrity as they would fail to post a winning record until 1990, despite posting a winning record; the Reds finished in second place every season from 1985 to 1989, failing to make the postseason.

Early 1990s: Return to competition/1990 NLCS

The Pirates began the 1990s firing on all cylinders led by the strength of All Stars: Barry Bonds, Bobby Bonilla, Neal Heaton, and Doug Drabek. The Reds had quickly become the surprise of the league, armed with their own dominant roster under new manager Lou Pinella, they boasted such talents as Eric Davis, José Rijo, Randy Myers, and Chris Sabo they dominated the division with a 5-game lead over the rival Los Angeles Dodgers.

1993-2000: Divisional Realignment/Decline

Following the 1990 season, The Reds declined mightily under the notoriously awful ownership of then-owner Marge Schott, the team saw multiple stars leave in free agency or fell victim to bad trades. Meanwhile; the Pirates managed two appearances in the NLCS in 1991 and 1992, ending in a loss to the Atlanta Braves both times. Due to the expansion of the league in 1993; the Reds and Pirates were both consolidated into the newly formed NL Central, turning their once heated playoff rivalry into a divisional battle. However; The Reds would only put up 2 winning seasons in 1994 and 1995, with a player strike and a sweep from the Braves in the 1995 NLCS sealing their decline. The Pirates would not manage a single winning season from 1993 to 2013.^[21] Despite a 1999 Wild Card appearance against the New York Mets, the Reds would not post a winning season from 2001 to 2009.

2010s: Return to Relevance

Following years of mediocrity and bad management on both sides, Cincinnati would manage a playoff appearance after 8 mediocre seasons, only to be swept by the Philadelphia Phillies. The Reds' new manager Dusty Baker would also guide the team to an appearance in the 2012 NLDS.^[22]

2015-2023: Decline for Both

The Pirates would manage two more postseason appearances following their run to the 2013 NLDS, they would lose to the World Series champion San Francisco Giants in a crushing 8–0 loss in 2014, and would go on to suffer another shutout loss to the Chicago Cubs 4–0 in 2015. Meanwhile; the Reds fired Dusty Baker on October 4, 2013, and Cincinnati has failed to post a winning record since 2013. The Pirates would fall victim to cheap ownership under Robert Nutting as numerous star players such as Andrew McCutchen, Starling Marte, Gerrit Cole, and Mark Melancon would all leave in free agency. During the 2019 season; both teams would engage in a massive brawl after Pirates' pitcher Keone Kela had thrown at Reds' batter Derek Dietrich in the seventh inning, the umpires would later give Kela a warning as Reds' star Joey Votto engaged in insulting the Pirates' dugout. Newly acquired outfielder Yasiel Puig would later go up to bat for the Reds before a controversial strike call from the umpire led to an argument between Puig and the home plate umpire. Frustrated with the call, Puig later threw down his helmet after several minutes of shouting, ending the inning. As Reds' pitcher Amir Garrett had taken the mound and had also engaged into a shouting match with the Pirates dugout after throwing at Pirates batter Chris Archer. After several minutes of shouting at the Pirates' players, Garrett charged the Pittsburgh dugout along with Puig; culminating in a massive brawl clearing both benches. Following the fight, Puig and Garrett would both be ejected from the game.^[23] In total: six players would be suspended a combined total of 40 games, including Puig and Garrett.^[24] An hour prior to the Pirates' final game of the 2019 season, manager Clint Hurdle was fired after eight seasons. Since 2015, only the Reds have made the postseason that being the 16 team postseason in 2020