Hey, I even got comfortable with the ISERROR!

To extract the middle name, work with the string in the full name starting after the 1st space, and try to deliver the number of bytes in the middle name: (position of 2nd space) - (position of 1st space) - 1. If this fails because there is no 2nd space, deliver a 0. This number becomes the third parameter of the MID function.

=MID(A16,FIND(" ",A16)+1,IFERROR((FIND(" ",A16,(FIND(" ",A16)+1))) - (FIND(" ",A16))-1,0))

To extract just the middle initial, look for a second space. If it's there, deliver the first letter of the middle name; otherwise deliver a null.

=IF(ISERROR(FIND(" ",A16,(FIND(" ",A16)+1))),"",(MID(A16,FIND(" ",A16)+1,1)))

Are we having fun yet?