I'm glad you explained it. I was looking at some other pitchers and although I knew the drag foot could leave the rubber before release of the ball, many of them are not remaining in direct contact with the ground prior to release. You're saying that it must remain "on plane", allowing it to pass above a divot, if a divot exists. I took it that they all must drag that foot regardless. I could see where Alex "crow hopped". I just looked around to see if other pitchers do it and get by with it. Several, without question, lose contact with the non stride foot before release... and do not get called.
Can a pitcher wear a clown shoe on the non stride foot? Can our robotics engineering team add a retractable toe extension that extends to touch the ground during the pitch? Can you add a dirt colored flap to the non stride shoe toe and meet the rule?