Grant is illegal but legal. The rule book states that pitchers may take one step back with their free foot and one step forward with their pivot foot for delivery. This has morphed into a step to the side and a step forward. Now, since there is no adherence to the rule, they are allowing a step that actually gains ground to the plate with their free foot before the step forward with the pivot foot.
I bet we are not far from seeing a person take a full stride forward with their free foot followed by another full stride forward with their pivot foot. MLB needs to get a handle on this before it happens.