"No progress occurs without change, but not all change is progress." - John Wooden
There are two advantages to aging, first a rather tenuous one that some people believe that through your experience, you may actually know something. Second, older folks have the advantage of having seen enough history and perspective to compare times directly, biased, but nonetheless reality-based.
Baseball, as a microcosm of society, has undergone massive changes. Player compensation escalated dramatically in the wake of the elimination of the Reserve Clause and initiation of Free Agency. This had tremendous benefits for all strata of player wages, with both the minimum and average salary spectacularly increased. As documented in the baseball history by Sean Lahman salaries had increased minimally from 1947 to 1965, and Marvin Miller's intervention led to Free Agency in 1975.
Although there have always been structural differences between franchise, this development significantly impaired the ability of 'small market teams' to compete on a more level playing field. It also caused dramatic increases in ticket prices that impaired the ability of the 'average' fan to afford attendance.
To quote Dave Studeman at The Hardball Times, "In May the Best Team Win, Andrew Zimbalist's fine book about baseball economics, the author found that the correlation between payroll and wins started to rise significantly around 1993. Before that time, the R-squared between payroll and wins floated between 0 and .3. Since then, it has floated between .2 and .6. In other words, the ability of teams to buy the pennant has really jumped during the last decade." In other words, despite Free Agency, competitive imbalance is a more recent product than simply a linear result of Free Agency.
In parallel with business and election scandal, neither of which were new, performance-enhancing drugs grew in popularity during the 1990s and beyond. The lure of unrestrained wealth is an easy-enough explanation for the corporate malfeasance of the nineties and into today (options redating and financial engineering) and MLB players' reliance on anabolic steroids, growth hormone, and other yet to be revealed technology. Obviously, overall player fitness increased through year-round training, weight training, and sport-specific conditioning as well.
The reliance of quantitative analysis (Sabermetrics) of baseball also has parallels in business, ranging from Six Sigma programs to quantitative measures of behavioral finance.
Despite the technological and pharmacodynamic applications, the overall quality of play hasn't necessarily improved. Scores and homeruns increased under the influences above, in conjunction with the live ball, smaller strike zones (somewhat reversed by uniform umpiring standards and Questec), smaller ballparks, the designated hitter (DH) in the AL, and generally declining pitching.
During the sixties and seventies, most teams used four-man pitching rotations. Using a five-man rotation automatically produces more games with marginal starting pitching. The addition of pitch counts (variably argued to affect performance and injury) also has produced more reliance on already overtaxed bullpens.
Charting player tendencies and optimizing defense and matchups has come to prominence over the past decade. Teams exhaustively scout and chart opposition.
Games became longer via more offense, the strategy of seeing more pitches, smaller strike zones, more pitching changes, and longer commercial times between innings.The advent of the DH altered AL teams' willingness and capacity to employ 'small ball', generally opting for the Weaverian three-run homer approach to offense.
Complete games became an aberration. No pitcher in either league has had double digit complete games in the 21st century. Fernando Valenzuela in 1986 was the last pitcher to have 20 complete games in a season. Up until 1980, the league leader in the NL almost invariably had a minimum of 20 complete games.
Pitchers' innings pitched gradually declined. The last 300 inning pitcher in the regular season was Steve Carlton in 1980. From 1951 to 1955 Robin Roberts pitched at least 300 innings for five consecutive seasons.
What hasn't changed is the use of technology to attempt to guarantee umpires making the correct call. About the furthest umpires use technology to make correct calls is to check a baseball to see whether there is shoe polish on a ball possibly hitting a player in the foot. Opportunities to use instant replay for incontrovertible evidence (subject to the limitations seen in the NFL) are: fair and foul hits (particularly concerning home runs), tag plays, running out of the baseline, close plays at first base, and 'catch or trap'.
All of which raises the question, is the game improved, worsened, or overall unchanged. I argue that the ballparks have improved the quality of the entertainment experience for the fans. Television broadcasts have far more sophisticated video, statistical, and graphical presentations. The prominence of international players contributions has improved the quality of the game.
However, ticket costs, strategy (incessant platooning) and technical changes that prolong games, late-night playoff and World Series games, and an overall decline in quality pitching have diminished the game. The game can benefit from circumscribed use of technology to improve umpiring, probably through a challenge system as in football.