Core-five RBI: The frustrating search for a new MLB metric

Mar 19, 2021; Glendale, Arizona, USA; Los Angeles Dodgers infielder Zach McKinstry against the Texas Rangers during a Spring Training game at Camelback Ranch Glendale. Mandatory Credit: Mark J. Rebilas-USA TODAY Sports
Mar 19, 2021; Glendale, Arizona, USA; Los Angeles Dodgers infielder Zach McKinstry against the Texas Rangers during a Spring Training game at Camelback Ranch Glendale. Mandatory Credit: Mark J. Rebilas-USA TODAY Sports /
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Mandatory Credit: Kyle Ross-USA TODAY Sports
Mandatory Credit: Kyle Ross-USA TODAY Sports /

Moving Forward with the Study

How could this study be moved forward, given that I had mislaid my supercomputer and could not literally study every possible “top” team, every possible .500 team, and maybe even every last-place team at discrete moments in time for, oh, five years or so?

Perhaps randomly selected dates were the answer. First, I decided to examine first-place teams, the six division leaders on entirely random dates.

These first-place, core-five RBI snapshots were taken on May 3 for A’s and Red Sox, on May 5 for the Phillies, who briefly popped above .500 to take first place alone, and on May 7 for the Cardinals, Giants, and White Sox (all after play).

Here were the results for the division leaders – team on the left, Core-Five Production (RBI per player per game on average) in the middle, total unqualified hitters in parentheses on the right:

Team                    C5P

OAK                       0.58 (1)

BOS                        0.67 (1)

PHI                         0.53 (0)

CWS                       0.66 (1)

STL                         0.57 (1)

SFG                        0.49 (4)

So, how does all this line up with the notion that a top team’s core-five RBI leader produces over 0.67 runs per game? Well, the figures are not quite there, but the season was still young after play on May 7, and the only true outlier to the 0.67-0.70 range was San Francisco.

But let’s look at the other apparent outlier, Philadelphia, first. In all three snapshots, the Phillies core-five hitters were driving in 0.53 runs per player – in a nearly month-long snapshot, in a five-game look, and in another seasonal look at a bit over five full weeks. Thus, despite leading the division at 16-15, their core-five production consistently suggested mediocrity for the early season.

Their one good sign was that as their third snapshot was taken, Andrew McCutchen was able to replace an injured Bryce Harper in the team’s top-five without an aggregate fall-off in “team” production.

Was this a tentative sign of fluidity in their core-five for RBI, thought to be a good sign for a team? Time might tell.

But what was going on with the Giants, the NL West first-place team at 19-13 after play May 7? A paltry 0.49 core-five RBI per top hitter each game?

Did this figure foretell a plummet for San Fran at some point? And what could be made of the fact that their core-five appeared to be completely unstable – four players among their five leaders on track to be ineligible for a home run, batting, or RBI title???

Did the Giants just need a bit more time to establish their “character”?