Your question betrays a fundamental misunderstanding of the biblical truth that there is nothing sacred about Sunday. Please read our article called 'The Real Meaning of the Sabbath' on the Traditions of Men shelf of the Apostolic Free Library.
The issue of playing professional sports is another matter altogether. To achieve that level of competency, most people have to totally give themselves over to their particular sport. This often results in the neglect of spiritual things. No one can serve two gods. There are also issues of modesty and Christian spirit (e.g. short pant in basketball and knocking people down in football).
All sports are not the same (e.g. golf is quite different from race car driving). But all sports have one thing in common: competition. The competitive spirit divides people, putting them of opposite sides, driving them to out-do each other. This is not the Spirit of God, and when this spirit dominates a local assembly, the obvious result will be division. This was the problem in Corinth, which is why Paul wrote, 'Now I plead with you, brethren, by the name of our Lord Jesus Christ, that you all speak the same thing, and that there be no divisions among you, but that you be perfectly joined together in the same mind and in the same judgment' (1 Corinthians 1:10).
It is not the day of the week that would concern us, but the potential fruit of playing professionally. If a person is mature enough to keep it all in proper balance, then praise God for His grace. If not, he ought to consider pursuing a different path.