As with most statistics there is a certain amount of interpretation required. My interpretation of the stats for QBs drafted #2 overall leads me to a different conclusion than yours.
There have been 4 QBs drafted at #2 overall in the past 20 years, which is as I admitted previously, a somewhat arbitrary range based on a previous conversation with another poster but that is what I have stats for so.
That said, those 4 QBS are: Marcus Mariota, Robert Griffin, Donovan McNabb and Ryan Leaf. I think we can all agree that McNabb's career, statistically, should be considered a success and conversely Leaf's career was an unmitigated failure. That leaves us with Mariota and Griffin. My personal opinion based on what I saw this year is that Mariota seems headed in the right direction so for the sake of argument I will put him in the successful category. Griffin is the wildcard. He certainly has the talent and has shown he can be successful. The question is whether or not he can rekindle that with Hue Jackson and Cleveland. If I had to guess, I would say that he will be successful enough to reach the average statistical range for a Top 5 QBs which is about 20,000 yards passing. He currently sits at 8,000.
So, out of those 4 QBs drafted #2 overall, here is how I see them based on their stats:
TD INT Yards RTG
Marcus Mariota 19 10 2,818 91.5 = Successful projection
Robert Griffin 40 23 8,097 90.6 = Average projection
Donovan McNabb 234 117 37,276 85.6 = Successful
Ryan Leaf 14 36 3,666 50.0 = Failure
So, I guess it depends on how you define "working out" as you phrased it but I would say that the stats suggest that the QBs drafted #2 overall have a little more success that you seem to believe.