Evaluating general managers in Major League Baseball is an incredibly tough exercise. There's the draft, free agency, coaching staff and trades, and every general manager deals with different constraints from prior regimes and from ownership. Because of those difficulties, we'll try a different kind of exercise aimed at evaluating and grading general managers solely on the results of the best and worst trades they've ever made.

We'll do our best to keep those moves with the team they currently run. Where the person in charge of baseball decisions isn't the general manager, the general manager will be in parentheses, with the grade going to the team's acting head of baseball operations. And beyond those grades, we've grouped them in four tiers that typify how well they've done -- and what their teams' fans can expect.