The odds of Pruitt becoming a starting point guard are .5%.
How would you know this? By your logic (and math) then, there shouldn't be more than one journeyman starter out of the 150 starters in the NBA.
Could anyone ever predicted that Ben Wallace would be a long time NBA starter after his rookie season? Or a Bruce Bowen? Or even a part time starter like Kelenna Azubuike, Matt Barnes, Devin Brown, Matt Carroll, Darrell Armstrong, Mike James, Anthony Carter, of a few years ago, etc, etc.