One bit of conventional wisdom in baseball is that talent tends to be evenly distributed among the different positions. This is more myth than rule because shortstops and first basemen aren't born; the people running baseball teams choose whom to play and where. David Ortiz probably would have been a terrible shortstop, but there was no law of physics preventing the Red Sox from calling Big Papi a shortstop.
Sometimes this talent distribution can change rapidly, reflecting a trend or a truth about what's going on in baseball. For example, when home runs became a powerful point of differentiation among players after the end of the dead ball era, which had been mostly about batting average, the smaller players at second and shortstop didn't add as many homers as the generally larger outfielders did. Same goes for third basemen, the hot corner being considered more of a defensive position than it is today.
Another trend is the decline in difference between players on the hard and easy side of the defensive spectrum. While the importance of talent up the middle to a team was always something you heard in baseball, it has been only since "Moneyball" that the WAR contribution from the middle positions (C, 2B, SS, CF) has finally caught up to the value from the corners. Before 2010, when up-the-middle WAR represented 50.1 percent of the overall WAR (FanGraphs flavor) in the league, the middle positions had passed the 50 percent mark only five times in 109 years, going back to 1901. From 2010 to 2017, it happened in six of the eight years.
You can also see the effect of baseball throwing off the traditional idea that any offensive contribution from a position is just the cherry on top. Teams don't generally throw in the towel on offense from any position these days unless they can help it. It would be much harder today for a player like Johnnie LeMaster, who put up a 66 OPS+ over 3,000 plate appearances from 1978 to 1984, to persuade his team not to research better options.