They hired him as HC not DC. I'm sure they were hoping he could do more than coach defense.
Regardless, there's no use in arguing with people who don't understand the position Lotulelei plays. I had it out w/multiple posters midseason who were adamant he would be benched or cut and that Phillips was the only guy worth playing, or that Peko would be able to step in and send Star to the bench lmao...and I maintained then and still do that the line relied more heavily on Lotulelei than anyone else. It's very obvious when you watch them in isolation.