He'll practice the parts of his game which he feels needs the most work. And if a statistician isn't aware of that, and if he refuses to account for that, it will hurt his forecasts. In the final weeks of the regular season he will overestimate such a team because he does not account for the teams' lack of a need to win. Moreover, in the playoffs, he will underestimate that same team because they posted such lousy stats in the final couple weeks of the regular season. Many statisticians refuse to ignore those games that aren't really indicative of how good a team really is.
Successful gamblers are more pliable, more resilient.
Successful gamblers use stats, alright, but they don't build inviolable rules for themselves. They aren't afraid to make subjective judgments in conjunction with their objective evidence. Sites that offer online wagering declare that they are legally licensed by the country in which their application server originates. Consult your local authorities prior to registering with any online wagering service.