Why Have There Been So Many Perfect Games Recently?

Never in Major League Baseball history have three perfect games been clustered within a year as those pitched by Mark Buehrle, Dallas Braden and Roy Halladay. These pitchers have pitched a "perfect game" in that they have retired every hitter that they faced for a 9 inning game. Is this the result of certain trends in baseball, or a sign of more to come? How did the recent developments in baseball management lead to this cluster? It does appear to be a confluence of recent baseball trends, while still being statistically unlikely.

League Expansion

MLB added 8 franchises in the 1960s, 2 in the '70s, and 4 in the '90s. The cumulative effect has been the diffusion of talent, which has resulted in different classes of players. The best players have a chance to be more dominant due to the talent difference being greater against the average opponent. Of course, this effect has been counteracted by globalization of the game and improved player scouting and development. However, it undeniable that quality starting pitchers are able to benefit from this trend. Starting pitchers often represent the best pitchers on a team and they cannot be avoided by their opponents (since good hitters can be walked rather than pitched to directly). Given the fact that great starting pitchers now face lineups with diffused talent, the trend of league expansion has led to seeing more dominantly-pitched games, with near no-hitters and perfect games.

Steroids and PEDs

The stain of the steroids era on the credibility of MLB records will last for quite some time. It will require several players acknowledged as "clean" to rewrite many of the power records. However, it is undeniable that many of the young major league hitters have been influenced by this era. The three recent perfect games have come against teams with young hitters (Buehrle and Braden faced the Tampa Bay Rays and Halladay defeated the Florida Marlins). During the power explosion years of 1998-2001, these players would have been entering high school or being developed as international Major League talent. In both cases, they were part of the MLB development process, where the y were likely encouraged to be the next Mark McGwire, Sammy Sosa, or Barry Bonds.

Talent Evaluation

Michael Lewis's Moneyball can be seen as having an effect on the development of the young hitters in the Major Leagues today. As this philosophy gained popularity among MLB front offices gained momentum in the mid-00's, franchises that began to further appreciate walks and home runs would also decrease the negative value attribute to strike outs. As such, a cohort of minor league players with a certain skill set in many organizations would spent their minor league years without having much value on batting average and making contact. Unsurprisingly, many of the members of the Rays and Marlins would have been in the minor leagues during these years.

Confluence of Trends

While none of these developments have permanently changed the game of baseball, the combined effect is that younger hitters approach the game and statistics in a new way. As expansion teams with fewer resources are likely to have a higher concentration of these types of players, these teams are at a higher risk of being exploited due to their lack of diversification in the players' approach. This makes it seem likely that they could be more likely to be the victim of perfect games and no-hitters. That said, it retiring 27 consecutive batters requires an intelligent pitching approach, solid defense, and many other bounces to go their way. These have come together for Roy Halladay, Dallas Braden, and Mark Buehrle, but perfect games are unlikely to remain at the high frequency of the past year.