You don't need full seasons to spot trends. We are not looking at statistical samples, we are looking at snapshots (an appropriate title to the link earlier). Snapshots are not random as a true statistical sample would be.
If we are trying to spot trends, it's perfectly legitimate to look at the equivalent of 30 seasons worth of data in a snapshot form because we are not necessarily trying to isolate seasonal totals; we are trying to determine what the current rates are (we can always extrapolate seasonal totals if the data set is large enough). I would say that there is enough data out there to suggest that the effect of the change has been significant. The home run rate is down everywhere I've seen. I haven't had the time to explore the numbers like some of you, but I can see a reduction in slugging for both of my franchises, including the minor leagues (although those are obviously less reliable indicators).
On the few occasions I've spoken up in this thread, I've mentioned that it still goes back to finding good players, not necessarily specialty players. And if you do have specialty players, you better have different types. I think the change is generally okay.