Kevin Warsh, the new chairman of the Federal Reserve, has made clear that he intends to change the way monetary policy works. Mr. Warsh has taken to the mantra that markets should “play the ball, not the referee.” The problem with this metaphor is that when it comes to interest rates, the fundamentals are the Fed. No wonder then that traders in Treasury bills and bonds focus closely on expected Fed policy. On inflation, Mr. Warsh is correct to insist on a reassessment of the models used before the inflation surge.