What you just said makes no sense to me, though.
Here's how I think it should be:
He starts season with 639 elite skill level.
So he's getting/losing whatever points he does, and that's getting him closer to his CURRENT SKILL (which you can't know before he plays any games).
There's nothing stopping him from improving his elite skill,
and whenever he starts winning more elite he will be rewarded with higher elite rating.
What makes you think the rating in season 2 (the one you don't know how be doing in) should be aproaching the rating from season 1 (the one you know how he did) in the first place? That's basically meaning we're projecting current results on the past ones, which is IMO flawed to start with.