This is apparently a long-standing street art theme - the umbrella image appears in some very unlikely places, but I've not encountered an image quite like this one. It is visible from the northbound lane of Lamar Boulevard, just north of the Town Lake bridge.
I've written before on the connection I find between the creative impetus in street art and the human need to make a special, if not always sacred, connection to place. What's the difference between an image like this and a graffiti tag? If a graphic or painting or installation forces us to take a fresh look or if we're compelled to react or remember, then that's street art at its best.
Psychologically, the umbrella is a symbol of protection. It can be a shield against a person's own feelings, or a symbol of financial well-being. An open umbrella in the rain can be an indicator of good fortune. No wonder the Travelers Insurance has used the umbrella as their logo. Perhaps this street artist is mixing the NBA with financial good fortune. In light of the current labor conflict, I think this artist may very well have been dreaming.
It appears that an NBA player is straining to reach, but instead of a ball or basket, he's got the open umbrella. Though the gesture was different, Mary Poppins did arrive and depart via umbrella.