While Mike Tomlin commands respect around the NFL, his detractors like to point out his absence of a coaching tree. We can debate the merits and validity of this as a criticism of a coach, but it’s also a fact. Tomlin does not have a robust track record of mentoring coaches who have gone on to do significant things elsewhere.
Part of that is related to the types of coaches he hires, which at times are older, or simply loyalists. But even when Tomlin has had some young coaches who generated some excitement, the Steelers moved on from them.