You probably already know that the guys who are better at controlling the zone were Harris acquisitions, and those who are worse at it were not. The roster we still have includes the best of what he inherited, and I'm pretty sure not many of those guys will be the long-term solution he has in mind for this franchise. He's had to keep them because he's always has to field a team today, but I would bet that Harris never envisioned Riley or Tork being the cornerstone of the perenniallly-contending Tigers franchise. Once the roster becomes more fully his doing, I think it will become more obvious how much better they control the zone than the team we see today.