Does it factor in DVR and internet stuff? Perhaps therein lies the rub.
I think "the rub" also includes the huge dead gap from the end of the fourth season to the start of the fifth.
Unlike ye olden days, when most shows aired 24 or so episodes spread out over many months with a summer break and a return in September, the shorter Lost seasons that start in January and air without repeats results in a huge off-season.
People can't keep track of a complicated show like Lost, particularly when they are asked to wait about 9 months between seasons.
Thankfully, even low ratings won't get Lost cancelled.