Not sure MacDonald applies...the Harbaugh's passed hot commodities back and forth to give them experience for the other brother. John would send Jim his "next DC" and let him learn in college. He literally was hand picked by John Harbaugh when he was like 26 years old to become a Head Coach in the NFL...
Not to mention MacDonald was what, 34 at the time hired and was correctly identified by a sitting long-tenured NFL Head Coach as a soon to be NFL Head Coach. John Butler is 51 and has been turned down as a DC for the last Decade+. They are not the same.
Martindale had been an ST Coordinator or DC since 1996 with brief stops as a position coach in between. DC'd NFL defenses in Denver, Baltimore, New York, and then Michigan. Again - not the fucking same.