There aren't many 767s left to be had on the charter market. Even NFL teams are struggling, and they really need the twin-aisle planes. The Patriots just bought their own aircraft to address the problem and some others are forced to use a pair of 737s instead of the 767s they used to fly.

And they don't need a 767 for a baseball team. Everyone still gets their own row on a 737; plenty of room inside.

Also, there are the DL 752s custom fitted for the NBA. Those are pretty nice inside.

Links to stuff I wrote; you've been warned.