Don't overestimate Michael's golf ability. When he was with the Bulls he played a lot of golf at a club I know quite well. There were a lot of days when his assistant was sent to the ATM and very few when he was on the upside. A nice club player with an inflated view of his abilities. Add baseball players to hockey players as a group whose skills tend to translate.
As far as the general topic goes, its pretty obvious that the general fitness level of players has gone up. Golfers always had excellent hand - eye coordination. But the immeasurable is how they would react in a game where movement is involved. Dustin and Brooks look like athletes and may be good at other sports. But the level of play at the Division I and professional levels is extraordinarily high. Don't confuse Nicklaus' decent play in high school or Watson's private school quarterbacking with those levels. Neither had the size or speed to move up. In any event, except for the rare multi-sport athlete, we'll never know. A few that weren't mentioned include Mike Souchak (golf and football), Dick Groat (baseball and basketball) Gene Conley (baseball and basketball) Wilt Chamberlain (basketball, track and volley ball) Jackie Robinson (baseball, football basketball, and track) and Jim Brown (football, basketball, lacrosse, track and baseball). In earlier times there was Jim Thorpe. But despite these examples and the others cited previously, when one considers the large number of people who have competed at the highest levels, the rarity of the talent exhibited by these multi-sport stars is magnified. It is getting harder with increased specialization. So I suggest that speculating on which athletes could have excelled at other sports, while fun, is unrealistic. However, think of some of the NBA players as soccer goalkeepers.