In 2006, the Mavs changed the complexion of the series by inserting Devin Harris into the starting lineup. Harris' penetration, defense and activity level were invaluable qualities for Dallas. That strategy is something the Spurs can borrow by playing Parker and Hill together for long stretches.
With a Parker and Hill duo, the Spurs suddenly won't appear as sedentary and unathletic. They can also better match the Mavericks' personnel and if they get out and run, that duo could help the Spurs get a few much needed effortless conversions in transition.