Rules Review - Passing a Base Requires Two Feet

The issue of passing a base took center stage when Replay Review confirmed 2B Umpire Doug Eddings' denial (safe call) of Philadelphia's appeal that alleged Marlins baserunner R1 Charles Leblanc passed and failed to retouch second base on a fly ball to right fielder Nick Castellanos and so that'll make it a 4-0 ballgame.

With none out and one on (R1 Leblanc), Marlins batter Bryan De La Cruz hit a fly ball to Castellanos in right field; with Leblanc running on the pitch, he arrived at second base before turning around to go back to first base to tag up. After the play, the Phillies appealed that Leblanc failed to properly retouch second base on his way back to first base, and that's where our past/prior rules discussion comes in.

In 2017, we discussed this same issue when Giants runner Brandon Belt was called out for running past second base on a similar fly-ball-to-the-outfield play, and, to summarize, the key concept is whether or not both of the runner's feet have passed the base in question before said runner has begun their retreat to a previous base.

Related Post: Past or Prior - Deciding When a Runner Has Passed a Base (7/1/17).

The MLB Umpire Manual holds the key to unlocking Official Baseball Rule 5.06(b)(1) (the retouch rule) and states: "A runner is considered to have passed a base if they have both feet on the ground beyond the back edge of the base or beyond the edge of the base in the direction to which they are advancing."

The accompanying diagram illustrates MLBUM's interpretation of what is considered past vs prior. At third base, the orange delineation line would be rotated 90 degrees counterclockwise to illustrate the same concept.

Video as follows:
 

Alternate Link: Miami's runner runs to, but not entirely past second base (one foot vs two) (PHI/CCS)