He will lose 9 points from Viña and 5 from Costa. And in that Memphis week he will need to win his first round to add a couple of points (10 points with a first round win, 35 with a QF spot).
And how is Del Potro losing Costa do Sauipe's points if the Brazilian tournament last year was held in the 8th week (the week when Memphis is played).
Buenos Aires and Costa changed weeks.
As I see it Del Potro will lose Buenos Aires and Viña's points and going to defend Costa do Sauipe's points in Memphis.