Yes. Both factor in, and neither is necessarily the exclusive answer.
Need to know and I don't. Nor do I care, really. The degeneration that happens over the years seems to happen only to the Pioneers, so it's not like it's a trend. No need for an extensive investigation as to why, and nobody would ever get paid for something like that investigation, which could take a very long time to conduct or research. It can't be changed now anyway no matter what the findings would be if investigated. You simply do the realignment and continue to enjoy your set, knowing that if it took 10 years to get this bad out of the box, chances are it will take another 10 years to go bad again. At which point the realignment can be done again.
Same with grayscale. It drifts off over the years because the colors degenerate at different rates. So realignment is needed every so often. Same with convergence. It drifts off and needs to be retightened every so often. Each point on a Mit convergence grid can be placed 522 clicks to the left of zero, 522 clicks to the right, 522 clicks up and 522 clicks down. That's over 2000 potential positions for each individual point to be placed in, on the 72 point grid. It drifts eventually. Why? Who knows! Who cares? It seems to be a factor of the ICs and their need to be burned in, which only really kicks in badly when new.
What causes a Lamborghini's tune up to drift off and need to be redone every so often? When you find the answer to that, maybe it will shed some light here too!
Edited by Mr Bob - 1/5/13 at 1:44pm