All major league contracts are guaranteed. So are NBA. NFL contracts are not guaranteed.
Michael Jordan almost did he played Mlb, Nba, and golf!
Hugo Bezdek coached a Rose Bowl winner, managed a major league baseball team, and coached an NFL team.
New York Giants- NFL San Francisco Giants- MLB
82 games in the nba, 16 games in the nfl, 162 games in the mlb.
Giants and Cardinals.
NFL is proven to have 2.3 times the ammount of viewers than MLB, in the united states.