Sometimes "ageing" doesn't mean that you can no longer perform, it could be that the hunger has gone, the hunger that young blood would still have. I'm not saying "past it", I'm saying that to me too many players don't look like they have the desire. Let's take last season for example, sh*t manager and yet those players (yes as you correctly put it the same players) still run the Manc's close and lets face it should have won the champions league, if they could get motivated for Grant then why not Scolari?
For me we need a shake up, give Scolari time and see what happens in the summer. If we're still in the same position this time next season then I would totally agree with the general opinion.