Manny Diaz spent one year at MSU in 2010 and during that season the Bulldogs had the 49th ranked defense in the country. MSU also had the 21st overall scoring defense, allowing only 19.8 points per game, which ranked 3rd in the SEC behind only Alabama and LSU. His most notable game that year was against eventual national champion Auburn when his defense held the Cam Newton-led Tigers to just 17 points. State went 9-4 that year and Diaz played a huge role in achieving that record.
Then Manny left for Texas, and who can blame him? The money was bigger and at the time, the Longhorns had a legendary coach at the helm in Mack Brown and were only two years removed from playing in a national championship game. But things slid downhill fast, after a fairly successful first season, Diaz's defense began to fall off and eventually he was fired following the second game of his third year, after his defense allowed BYU to rush for 550 yards against the Longhorns, the most rushing yards in a single game ever allowed by a Texas team.
Diaz then moved to Louisiana Tech where he was the defensive coordinator for the 2014 season before making the move back to MSU. His LA Tech defense performed well, finishing 35th in the nation and 2nd in the CUSA in total defense and 17th nationally and 1st in the CUSA in rushing defense.
Now Manny Diaz is back in maroon and white and Geoff Collins left him with an excellent stable of players to work with. But how does Diaz's one previous season at MSU and the years he spent coaching Texas and Louisiana Tech stack up against MSU's last four years? To make this comparison, I averaged all three of the major defensive measurements (passing, rushing, and scoring defenses) and their national and conference rankings over the last 4 years for both Diaz and MSU. (I included Diaz's 2010 season and omitted his 2013 season since he only coached two games that year at Texas) Here's how it shook out:
Diaz 2010-2012, 2014
Total defense: 357.2 yds per game (Ranked 41st nationally, 4th in conference)
Scoring defense: 23.98 pts per game (Ranked 41st nationally, 3rd in conference)
Rushing defense: 131.23 yds per game (Ranked 32nd nationally, 3rd in conference)
Passing defense: 225.98 yds per game (Ranked 65th nationally, 6th in conference)
MSU 2011-2014 (Chris Wilson, Geoff Collins)
Total defense: 377.93 yds per game (Ranked 48th nationally, 8th in conference)
Scoring defense: 21.93 pts per game (Ranked 26th nationally, 6th in conference)
Rushing defense: 153.69 yds per game (Ranked 53rd nationally, 7th in conference)
Passing defense: 224.25 yds per game (Ranked 53rd nationally, 9th in conference)
And to ease your mind about MSU foregoing Ed Orgeron as a defensive coordinator candidate, here are Orgeron's numbers from his 2010-2013 seasons at USC. (It obviously has to be noted that he was not actually the defensive coordinator for the Trojans, he was the defensive line coach, but nonetheless):
Total defense: 375.93 yds per game (Ranked 53rd nationally, 5th in conference)
Scoring defense: 23.95 pts per game (Ranked 41st nationally, 4th in conference)
Rushing defense: 134.79 yds per game (Ranked 38th nationally, 5th in conference)
Passing defense: 241.10 yds per game (Ranked 74th nationally, 6th in conference)
When compared, Diaz's teams unanimously beat MSU and Orgeron in total defense and rushing defense. His passing defenses are right on par with MSU and again they beat Orgeron. Diaz comes in 3rd in scoring defense but the difference is miniscule especially when compared to Coach O.
It's clear that Diaz's defense is capable of not only being just as good as MSU's defenses since he left, but he has the potential to be even better. So, no matter how you feel about this prodigal son returning to the place that he abandoned after being offered a job at a bigger school, the numbers don't lie and Manny Diaz was the right man for the job.