from illegitimate excuses, then fix the legitimate excuses."

Why is your team under performing?
They will come up with some illegitimate excuses (many of which are just an excuse to be lazy), but they will also come up with some legitimate ones.
"Our pricing is too confusing for customers."
"Our slide pitch deck is terrible."

A good manager finds those and then learns and improves.

The giant list you provided should be separated into two distinct categories:

Players that would have gone to BYU if BYU had done a better job of recruiting them, and players that were never going to BYU no matter what.
There is nothing for BYU to learn from Manti Te'o or Cam Latu. BYU gave it their all. They couldn't have done anything differently.

Here are players that BYU really screwed the pooch on...
Most of these are a bad evaluation and or poor recruiting effort because BYU didn't put in that effort.

Also, this is based on cougarboard rumors and some insider knowledge in a few cases...
Covey: Misevaluation. Utah and Kyle made him a priority, BYU didn't. Allegedly because Anae thought he was too small. BYU simply speaking got out recruited here.
Matt Gay: Reached out to BYU and was told "we already have a kicker, no thanks." How hard is it to meet with the kid? Lack of effort. I think Andy Phillips was a similar situation.
John Ursua. BYU didn't think he was good enough. Utah made the same mistake, if it makes us feel better. Recruiting misevaluation.
Spencer Fano. Lack of effort. BYU knew he would be good, but there was the ticket fiasco and he was just never made to be the same priority as Utah made him with the helicopter to games, etc., This may have been a two-for-one if it cost BYU Logan Fano as well.
Garrett Bowles. Depends on who you believe. He was an early BYU commit and grew up a fan, but also his girlfriend/wife was a Utah fan, so some say he never would have gone to BYU.
Kyler Fackrel. Miseval. BYU didn't think he was good enough, USU was his best offer.

I'd also add Nephi Sewell. BYU could have had him but didn't think he was good enough to offer out of HS, (neither did Utah, he went to Nevada before his mission). So recruiting miseval.

As an aside, I think BYU should look at every LDS kid that commits to USU and Utah and anywhere else with an extra level of detail and give them an additional look, just in case. Perhaps if they had spent more time on Fackrell and Nephi Sewell and Ursua to name a few they would have changed their mind and offered and locked them in. It is unreasonable to expect them to bat 1000 on all LDS recruits, but they can't misevaluate so many.