they're more good than lucky.
It's interesting, the luckiest rankings look at things like turnovers and special teams' scores to determine that a team may be overperforming in a way that it hard to replicate. Supposedly, they look at things like offensive and defensive efficiency ratings and then high performances over those in a win could indicate "luckiness" occurring. A lot of close wins can also factor. Not sure what reamrankings does, but assuming it's heavy on turnovers and ST scores.
BYU's forced turnovers and special teams play comes more on skill rather than luck. 1) Special teams execution has been fantastic, not just on scores, but on fakes, coverage, etc. Parker Kingston's td return obviously started with the ball on the ground, but still had some outstanding blocking/execution to return that. 2) Someone could go back, but I think a large percentage of the turnovers should definitely be credited to BYU's blitz and coverage disguises. A much smaller number of these turnovers seemed more like gifts.
Oh, and guess whose ranked as the most unlucky team in the nation? Kansas. It would be interesting for someone who knows Kansas football to be able to comment on lucky vs unlucky turnovers; or good vs poor STs coverage/execution.