Provide a link to the quote above, because every thing I've read and heard them say is the exact opposite. I listen in on SportsNation every morning at work and I listen to all the Coordinators Corners with Greg Wrubell. Maybe I missed something, but I know for a fact I've heard both Detmer and Sitake explain why it's better for Mangum not to redshirt. The closest thing I can think of is that Sitake said he wishes he could keep Mangum at BYU for as long as possible...forever basically. He said he wished he could keep all his good players forever, but that's not what's best for their careers. And his players' careers are what's most important to him. This staff places a noticeable emphasis on prepping guys for the next level. Perhaps you misinterpretted this sentiment to mean that he wanted Mangum to redshirt, but that is clearly incorrect.
I'm all about discussing all things BYU, but this whole Mangum redshirting debate that happens on CB just peeves me. Mangum made it clear that he wants to go to the NFL in two years and does NOT want to redshirt. Sitake and Detmer have both expressed their opinions on the matter saying Mangum will not redshirt because they feel that's what is best for him. Mangum does NOT want to be a 26 year old entering the draft...that's ridiculous. Yet we've got people on CB criticizing this decision...and it peeves me. Hence my response.