Why Nimitz declined the Pacific command before Kimmel

Chester Nimitz was offered the Pacific command before Husband Kimmel but managed to decline it. The assignment appears to have been hazardous enough that accepting it was not an automatic career prize. One interpretation is that Kimmel accepted after Nimitz refused because he feared command might otherwise pass to William Pye or another less suitable officer. The episode adds context to Kimmel's appointment and to Nimitz's rapid willingness to replace Pye after Pearl Harbor.