I looked into his stats because I don't pay much attention to the Knicks.
At any rate I think Jeremy Lin is definitely going to have a good deal of trouble succeeding long term. There are a number of concerns there, but by far the biggest is TOs. In each game he's played, he has had the most TOs of any player. You can coach that away but one of two things will happen, his FGs will go up and his ASSTs will go down, or his ASSTs will go up and his FGs will go down. What you want, for a lot of reasons that most of you probably already know, is for the latter to happen. What seems to be happening is the former. There is a reason it is called a Point Guard. That needs to be fixed or other coaches will definitely take advantage of it when it counts.
You say, "well no problem...when Stoudemire and Anthony get back the problem will ameliorate." It may. I don't know. I would have to revisit his stats at that time. If I had to bet, I would bet that it will get better. But other young PGs struggle with the same issue...to the detriment of their teams in my opinion.
I guess what I am saying is that success in basketball, as measured in rings, requires stats optimized for balance and flexibility rather than strength. When Jason Williams finally got to Miami he was a more balanced PG. IIRC, during the 2006 finals he averaged 12 points and 7 ASSTs. Critically, at that point in his career TOs were under control. Jason Williams peaked at, somewhere around 3.5 a game. Jeremy Lin is averaging twice that at least. Not good. And consider, Jason Williams could make some of that up on the back end with steals. Not so much with Jeremy.
So I can see why a lot of statisticians would look at Jeremy Lin and say,"...well with my personnel...I'll have to pass on this guy." Of course if we scour the web we will find one guy who rated him highly, that is the nature of the beast. But there are a lot of good reasons that a lot of good scouts did not rate him highly. And most strategists probably see a lot of those reasons every time he plays.
All that said, Jason Williams, after initially playing a lot like Jeremy, achieved a REALLY good ASST/TO rating. If it wasn't THE highest...it was close. But again, that's the 12 points 7 ASSTs Jason Williams, which is what you want in a PG if you want to get to a ring.