I think these are the reasons the Spurs are interested in him:
“great quickness...Can make some truly spectacular passes....Extremely quick...Good floor vision... Has a tremendous innate feel for the game,....Quick hands on defense..... good lateral quickness and length... “
These are things that normally can't be taught. And they are the skills of a natural point guard. Not only do the Spurs do not have a settled backup point guard, Tony Parker is not a natural point guard either. That is why Manu is relied upon to be the play maker a lot of times.
Of all the point guards on the roster only DeColo has the court vision and passing ability to be a play maker, but he lacks the natural abilities to be a good defender. Note that in addition to his play maker talents Myck has quick hands, good lateral quickness, and length, all necessary for good perimeter defense.
He has not developed his talents much yet and so he is not of much use in the NBA right now. I do not believe that the Spurs are looking at him for this year but as a development project with the hope that they produce a true point guard that can at least serve as backup for Tony. For that the Toros may be the best place for him.
At one time MK was considered by some to be a potential lottery pick. However, the scandal derailed all that and he went undrafted. This is just another case of the Spurs looking for low cost options with a high potential payoff.