I get that some folks won't be able to get past the fact that he coached at Auburn, but...
During his last three years as a DC, Chizik's teams went 36-3 (.923) including two undefeated seasons (04 and 05 - at two different schools, no less). The three losses in 2006 came by a combined total of 26 points (8.6 points per loss).
By way of comparison, Smart's last three years as DC at Alabama yielded a record of 37-5 (.881) with the five losses coming by a total of 39 points (7.8 points per loss).
From Wiki: "His 2004 defensive unit led the country in scoring defense, giving up 11.3 points per game, and the total defense ranked 5th, which is the same ranking the 2003 team recorded. He garnered the 2004 Broyles Award, which is given each year to the top assistant coach in the nation. The 2004 Auburn Tigers football team finished 13–0 that year, won the SEC title, and defeated Virginia Tech in the Sugar Bowl. It placed second in the final AP and Coaches polls.
In 2005, Chizik was hired by Texas to serve as their co-defensive coordinator, assistant head coach, and linebackers coach. During his time at Texas, the team won the 2005 NCAA Division I-A national football championship by defeating USC in the 2006 Rose Bowl."
Serious question - what else would he need to do to impress you as a DC?