It totally depends on ones understanding of the word "better". I'm sure some would argue that he has in fact improved, due to how he routinely socializes with people other than his parent(s) and what not. I would say that this new-found "socialization" is basically all bullshit, since he still lacks the most basic foundations of what one would call "social skills". Any time Chris interacts with another person, his mannerisms are based 100% on rote memorization. In other words, over time he has learned that saying certain things will either get him a positive or a negative consequence (completely lacking any sort of real understanding of the relevant whys and whats). It is through this trial-and-error type of learning (I hate to even call it "learning" in his case) that Chris has gotten to where he is now socially.
That is the very definition of socialization (in the sociological context), which is the most common and continuous form. It is the most basic form of learning that most every human being who isn't in continuous social isolation experiences every day.
Perhaps Chris lacks a developed theory of mind, one of the most basic traits of any socially capable human being, but that doesn't mean he isn't learning. Trial and error may be the only way for Chris to even be socialized, recieving sanctions for unwanted behavior and possitive attention for wanted behavior. Chris, under the assumption that he can't fully understand that other people operate differently than himself, is wholey religated to this trial and error method. If he had a functioning theory of mind, he'd be along much further socially.
The funny thing is, the way Chris is developing his social capabilities is exactly the same way most human beings, yourself and myself included, develop theirs. The big difference is that we developed a functioning theory of mind and have the capability to make inferences, and Chris didn't.
The way Chris is learning socially is only different from our own in the degree of inference.
All of that aside, isn't an increase in social competence, regardless of the cause, an improvement? If He became more social by using Meth, it'd still be an improvement.