Back in the late 90's, early aughts, it was almost impossible to read an article about the business of Major League Baseball without it focusing on how the sport had serious issues with parity. It seemed as though every other article on baseball detailed how only large market teams with high payrolls could make the playoffs, and the small market teams didn't have a chance. The book "Moneyball", published in 2003, was all about the way the Oakland A's succeeded in being one of the few small market teams that were able to win consistently.
Being a Midwesterner, I could see first hand how the baseball franchises of the Rust Belt cities struggled mightily. The Reds went fifteen years between playoff appearances, while the Pirates went twenty years without posting a winning record. Other small markets, such as Kansas City, also saw their teams suffer decades of futility. In recent years, things have turned around for several of these small market franchises. The Reds have made the playoffs 3 times in the past four years, the Pirates finally achieved a winning record last year, and this season the Kansas City Royals are competing for a playoff spot.
While the teams mentioned above have succeeded because they finally got their acts together in terms of developing players, I can't help but wonder if the recent crackdown on steroids and HGH in the recent years has helped improve baseball's parity problem.
An expensive baseball team is usually an older baseball team. Players have to accrue six years of service time at the major league level until they are permitted to become unrestricted free agents. Since most good players come up to the majors around the age of 22, they are not free agents until they hit the age of 28, which is right in the middle of their prime years. So at the age of 28 they go off and sign a high salary, long term deal with a large market club, maybe the Yankees or the Angels. The problem for the large market clubs is they get about two years of that player's prime before they hit the wrong side of 30 and start to decline. Also, as players age and their bodies break down they tend to spend more time on the disabled list. This might not have been such a problem when Performance Enhancing Drugs (PEDs) were rampant in the sport. Steroids could help prevent the normal decline that came with age while HGH could prevent trips to the disabled list. Now, with drug testing having been instituted, large market teams are having trouble with their older players not being as productive as expected, or missing more game with injuries. This has allowed the small market teams with younger players a chance to compete.