the "no work on Sunday" rule should (in the words of many prophets) be restricted to those professions (i.e. doctors, nurses, the President, military duty, 24/7 security, etc.). LDS athletes who choose to work on Sunday in the NFL or NBA or wherever are stretching this a bit. It's not going to keep them out of the Celestial Kingdom, IMO, but it's definitely not good for their spiritual welfare and extra care should be taken by these individuals to make sure the rest of their Sabbath brings them closer to Christ.
We all do things that separate us from the Spirit, and working on the Sabbath when it is not necessary is one of those things.