Since you do know who is the best pitcher and who the best hitter, you need not select them. Their position is already _fixed_. Remaining $7$ people can be arranged in $7$ positions in $7!$ ways.
Since you do know who is the best pitcher and who the best hitter, you need not select them. Their position is already _fixed_. Remaining $7$ people can be arranged in $7$ positions in $7!$ ways.