At least J first names would be strong
First through was Cliff Johnson at catcher may as well have Dale Murphy at catcher. But there is absolutely nothing else (unless I'm missing someone who came along very recently)
Dave Johnson at second, maybe? If post-41 only are they really reduced to Deron Johnson and Bo Jackson?
Another fairly easy one to put together
Piazza
Pujols
Priddy
Pesky
Palmer, Parrish or Pendleton at thirdbase, they're all the same to me (can't bring myself to allow Perez)
Piniella
Puckett
Parker
Jim Palmer and Perry