I'm thinking there are at least 2-3 losses over the Miles tenure that have potentially costs either a title or a shot at a title. This is what frustrates me and most fans in my opinion. We have had top-5 talent every year and it FEELS like we should have been to and won at least one more title.
Most programs would dream of being in the hunt for a championship in 6 seasons over an 8 year tenure. Of course there are frustrating losses during a coaches 8 year tenure. This is college football, and every loss is frustrating because it means so much.
Your problem in your argument is that every major program has these frustrating losses over a period of time that did or could have cost them a shot at the bcs championship game. Here are some examples from just this season:
Florida lost to UGA - had a ton of turnovers
Bama lost to A&M - Passed the ball inside the 10 year line
Oregon lost to Stanford - Couldn't get offense going and didn't make any offensive adjustments
UGA - Got smoked by South Carolina 35-7
Florida St. - Lost to an unranked NC State team
All of these teams mentioned have close or comparable talent to LSU, and the only one that played as tough a schedule this year is Florida.
Every program has "the ones that get away." Miles is not a perfect coach, but he is still a great coach. With a bowl win, he will finish in the to 10 in 6 of 8 seasons and possibly in the top 5 in 5 of 8 seasons. That is pretty remarkable.