As the 2015 Major League Baseball season dawns, the lords of baseball are asking for our forgiveness. They want a second chance, and to get it they are making changes that could shake the game to its foundations.

This isn’t about tinkering with the playoffs to make a few extra dollars from the television networks. The 30 team owners have ordered the new commissioner to modernize baseball and make it appeal to an audience that is increasingly weary of the game’s slow pace. There will of course be cries of sacrilege from traditionalists...