Foster looks at NBA draft selections to show how much Michigan BB players have fallen off.
But, anyone looking at the graph can see that the decline coincides with an incline of foreign-born players in the NBA draft. 20-30% of the spots go to non-US players now, as opposed to when Michigan was having multiple players drafted.
While there may have been some decline in BB players here, it is not nearly as bad as Foster makes it seem for his article. Sometimes doing analysis the right way makes your story less interesting, so you just don't do that work.