MLB: How baseball has changed over the decade

Adding up the stats

One decade ago, nobody analyzed a pitcher’s performance on the basis of ERA+ because that stat didn’t exist. Linear weights – which measures the contribution of every offensive outcome to run production – did exist; it was developed by Pete Palmer in the mid 1980s. Its use, however, was confined to eggheads.

But with the popularity of such sites as Fangraphs (launched in 2005) and such stat-focused TV shows as MLB Now (2013), interest in the statistical analysis of baseball has spread rapidly.
As recently as 2006, Minnesota’s Justin Morneau was able to win the American League’s Most Valuable Player Award despite finishing outside the top 10 in all of the following statistical categories; batting average, home runs, WAR and OPS+.

He triumphed for the kinds of perceptual reasons that used to govern MVP awards: He was an offensive leader on a team that won its division while improving by 13 games over the previous season.

Today, the value of each player is extensively – and largely accurately – reduced to a single number by any of several metrics that either did not exist or were little known a decade ago. Those metrics include Win Probability Added, Weighted Win Expectancy, Barrel Rate, Chase Rate, Exit Velocity and Launch Angle…plus a couple dozen more. WAR and OPS+ are merely the most widely understood of that increasingly vast collection.