Power is such an important component of today’s game that a scout recently told Baseball America that he hesitates to recommend any player for whom he cannot project at least fringe-average power. That’s a 45 on the 20-80 scouting scale, and it translates to roughly 10 to 12 home runs per season.

This pertains to corner players, of course, but even up-the-middle players hit for power today. Here are the seasonal rates for players at all eight field positions over the past three seasons, 2014 to 2016, where DT stands for doubles-plus-triples:

The scout is not only correct in his valuation of power—even the league-average shortstop hits 13 homers per season today—but if anything he undersells the importance of power. That’s because the complete data set in the table above includes even those players who failed to hold down jobs. The average home-run output for regular position players is higher.

In other words, the data supports the thesis that major league teams select their regulars based in large part on power production, even at positions such as shortstop or second base where defense is critical. Has this always been true? Baseball-Reference.com makes it easy to find out. According to the site’s splits data, here are the three-year rates for home runs per 650 plate appearances at each position.

The % Change column measures the percentage growth in home-run rate from the earliest sample period (1974-76) to the most recent (2014-16), a spread of 43 seasons. The StDev column stands for standard deviation, which will come into focus a bit later.

Players today at all positions go deep more often than players from the 1970s or 1980s—a fact that should surprise no one—but what’s most striking is the rate of grown for middle infielders.

• Shortstops today hit 225 percent more home runs per season than they did in the 1970s—and 18 percent more than they did 20 years ago.

• Second basemen today hit 133 percent more home runs per season than they did in the 1970s—and 40 percent more than they did 20 years ago.

Narrowing The Gap

Virtually the same number of home runs are hit at the eight field positions today as were hit 20 years ago, but the shape of the output has changed. Middle infielders have improved their home-run output by 29 percent since the mid-1990s, while corner outfielders have fallen 14 percent in that time. Home-run rates are fairly static—if down slightly overall—across the other four positions in the past two decades.

The following graph isolates the home-run rates for corner outfielders and middle infielders, because those two groups have experienced the largest swings in production.


Middle infielders keep finding a new gear each decade in terms of home-run production, while corner outfielders plateaued in the mid-1990s through the mid-2000s (44) before dropping off slightly (38) in the mid-2010s. In fact, corner outfielders today hit 16 percent fewer homers than they did just 10 years ago, and the power-production gap between their group and middle infielders has narrowed steadily and consistently over time.

Consider this: Corner outfielders hit 180 percent more home runs than middle infielders in the mid-1970. In the most recent three-season sample, corner outfielders out-homered middle infielders by just 41 percent. Even 20 years ago, the production gap was 110 percent in favor of corner outfielders.

Leveling The Field

Remember the standard deviation referenced above? What that statistic measures is the spread of values in a data set. In this case, the spread of home-run values between the positions has narrowed considerably over time, which means that more positions today are closer to the mean—the league average for home runs—than ever before.

This is a new phenomenon. The standard deviation between positions today (3.7) is smaller than it was even a decade ago (4.5) and much smaller than it was 20 years ago (5.5). This means that teams truly receive power from all positions today like never before.

The data argues that while the expected level of power production still varies by position, the distinction between positions is less meaningful than ever in a world where shortstops and second basemen now deliver 13 to 15 home runs. This supports the scout’s assertion that prospects ought to show at least 45-grade power potential in the minors or, if they don’t, have one or two other tools that grade as 70s or 80s to have any hope of assuming regular play in the majors.