Except that Les Miles is an offensive coach. He is a former OL as a player. He was an OL coach for Michigan and Colorado in the 80s and 90s. Was OC for Colorado in the 90s, had some ideas but the head coach wouldn't listen to him so he split and was a TE coach for the Cowboys. Then he came back to Oklahoma State after they fired the head coach that wouldn't listen to him and put in what at the time was a very innovative power spread offense, as virtually no one was running a power spread offense ... back then the spread was either Mike Leach run-and-shoot type passing offenses, or Rich Rodriguez and Chip Kelly speed option offenses that attacked the edges ... no one was doing power running out of two back and I-formation offenses before Miles except maybe Ralph Friedgen, although what Friedgen ran at Maryland and Georgia Tech couldn't really be called the spread because they took a lot of snaps under center. When Miles had Jimbo Fisher helping him recruit and more importantly DEVELOP players at LSU, his offenses were great. But when Fisher left, Miles made a string of bad hires at OC and QB coach, which led to his offense falling apart.
The defenses at LSU ... Miles never had a thing to do with them. His defenses at Oklahoma State weren't that good; they just relied on outscoring everybody. His early years at LSU, he still relied on the talent that Saban had put in place, and he got Bo Pelini to be the DC. After Pelini left, he hired John Chavis, whose defenses carried Tennessee for a long time, but Chavis' defenses became outdated and weren't nearly as good when Chavis left as they were when he got there, and still had Pelini's players. By the time that LSU finally got sick of Miles and fired him - which should have happened 3 years ago when he refused to fire his best friend OC - LSU's defenses really weren't all that. They just LOOKED good because of all the future NFL talent on them, and because SEC offenses have been terrible for going on 10 years, or at least they have been terrible at the SEC schools that recruit the best players (Auburn, Alabama, Tennessee, Georgia, Florida and yes LSU) while some of the middling schools that don't get good talent like Ole Miss, Mississippi State, Kentucky, South Carolina, Missouri, Arkansas and even Vanderbilt have actually had better offensive coaching.
If you hire Les Miles, make sure that it is for recruiting and running a program only. In particular you will want to choose his OC for him in advance. Maybe the Wake Forest OC would be a good guy to pilfer.