Best All-time General Manager: The GM Rating System: An introduction

We will look into the best all-time general manager through an objective system that gives a true indication of the best of all-time. This is an introduction of that system!

On-field talent is the single most vital determinant of a team’s success, and the general manager is the person generally charged with acquiring that talent. Until now, however, nobody has developed an objective and comprehensive method for determining how well GMs have performed or the best all-time general manager.

The GM rating system debuting here measures the performance of every general manager in Major League Baseball history who worked in that job for a minimum of five seasons. As of the conclusion of the 2017 season, that encompassed nearly 180 persons. Not all of them, by the way, held the title of “general manager.” For many years teams did not have GMs; their personnel decisions were made by owners or by field managers.

In recent years, too, the question of decision-making responsibility, which is central to any GM rating system, has more than often been a muddy one. When the Atlanta Braves dominated the NL East through the 1990s and beyond, who got credit for the player acquisition decisions, GM John Schuerholz or field manager Bobby Cox? On Chicago’s North Side today, is that the job of GM Jed Hoyer or of his boss, president of baseball ops Theo Epstein? Who’s making the deals in Oakland, baseball ops president Billy Beane or David Forst, the A’s general manager?

For purposes of this exercise, the assumption will be that if a team appoints someone as “general manager,” that person’s fingerprints are on the personnel decisions. If you remain bothered by this distinction, feel free to think of the GM rating system as a “front office rating system.”

Beyond that obvious point of contention, The GM rating system is comprised of eight measurements, the sum of which becomes the GM’s rating. All eight are entirely objective; opinion has no role in their calculation. The eight are:

1. The standard deviation of the average annual short-term impact of a GM’s personnel decisions compared to the average for all GMs included in the study. (See definition of “short-term” below.)
2. The standard deviation of the total short-term impact of a GM’s personnel decisions compared to the average for all GMs included in the study.
3. The standard deviation of the average annual long-term impact of a GM’s personnel decisions compared to the average for all GMs included in the study. (See definition of “long-term” below.)
4. The standard deviation of the total long-term impact of a GM’s personnel decisions compared to the average for all GMs included in the study.
5. The standard deviation of the average annual residual impact of a GM’s personnel decisions compared to the average for all GMs included in the study. “Residual impact” is defined as the impact of moves made by a former general manager, again measured in Wins Above Average.
6. The standard deviation of the total residual impact of a GM’s personnel decisions compared to the average for all GMs included in the study.
7. A scaled award or penalty for the number of seasons, if any, a general manager’s personnel decisions exceeded the number of games by which his team either qualified or failed to qualify for post-season play.
8. A scaled award for post-season berths earned. The scales referred to in points 7 and 8 are based on the awarding of one point for each eight teams in competition for one playoff berth. In seasons when more teams are competing for more playoff berths, the award may change proportionately. Variations across the years in both the number of teams and the number of post-season sports require the use of a sliding scale, but since the addition of a second wild card in 2012, meaning that each league has 15 teams competing for five post-season berths, the value has been 0.38.

Why use standard deviation? 

Standard deviation is an excellent tool for cross-era comparisons because it normalizes all the “change over time” factors that might otherwise muddy such comparisons. It deals with the question of whether any specific modern general manager was better than a predecessor by asking how superior each is or was in comparison with contemporaries.

This is a valid approach because many changes in baseball have taken place over the decades, both current and former general managers can be assumed to have operated with fundamentally the same knowledge set as their contemporaries.  Interpreting standard deviation is akin to reading a classic bell curve; the farther toward the edge of the bell, the better (or worse) the GM.

In simple terms, a general manager who rates +1.00 in any category can be thought of as superior to about two-thirds of the field in whatever skill is being rated. A general manager rating +2.00 is superior to approximately 90 percent of the field. A rating of +3.00 indicates superiority to about 97 percent of contemporaries. Anything above +4.00 is off-the-wall good.

Why use Wins Above Average rather than WAR?

Impacts of GM moves are measured by the Wins Above Average of the players involved in the moves. Wins Above Average has the same characteristics as WAR with one exception: rather than being based on the projected performance of an average minor league callup, it is based on the performance of an average big league player. That means it’s zero-based. For the purpose of cross-era ratings, that’s good.

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Defining the Terms

Short-term impact: The impact of any player-related move, measured in Wins Above Average, if the player move occurs during the season in which the move is made (if made in-season), or in the immediately succeeding season (if made during the off-season).

Long-term impact: The impact of any player-related move, measured in Wins Above Average, that occurs following the season in which the move is made (if made in-season), or following the immediately succeeding season (if made during the off-season). If the player is dealt or otherwise lost, long-term impact accrues on a sliding scale over the first five seasons following the short-term loss, unless the organization re-acquires the player within that time frame, in which case the calculation is halted.

Residual impact: The impact of any player-related move, measured in Wins Above Average, when that impact is felt following the GM’s departure from the general manager position. Example: A GM signs a player to a multi-season contract and then leaves the organization two seasons later. In that case, the player’s value would be assigned to the GM thusly: Season one, short-term; season two, long-term; seasons three and beyond, residual.

The best all-time general manager series will begin with Andrew Friedman in the next post!