Sure, he could play the whole season (thanksfully no serious injury *knock-knock on wood*
) but Kiwi didn't perform well enough in the Masters this year; one quarterfinal and that's the end of the story. Three Grand Slams were quite okay and there would have been more possible if Federer wasn't all the time in his way.
Ferrer has made two Masters semifinals, a Slam QF, good results overall on clay.
Puerta and Johansson posted both big results at a Slam, what Kiwi couldn't do, something like that helps enormously and if you have such a result in your ranking, you are forgiven again lots of other bad results. They all did have some stand-out results that Kiwi didn't have in big events and deserve it to be ranked that high although we know that Kiefer could do the same, regarding ability, talent, where he was once.
As for Stepanek, his ranking will drop also if he can't defend his Masters finals points this week from last year.
Like you say, Australian Open next year is a good possibility to gain points and to make up for the first round loss against Rochus from this season