If you look at the combined SCOTUS appointment by Reagan, GHW Bush, and GW Bush:
Reagan: 1-0-2 (0.667)
Scalia +1 (win)
Kennedy 0 (tie)
O’Conner 0 (tie)
George HW Bush 1-1-0 (0.500)
Thomas +1
Souter -1
George W Bush 2-0-0 (1.00)
Roberts +1
Alito +1
Total: 4-1-2 (0.710)
Even with 3 Moderate to Conservative presidents, 0.71% of the time you are going to get a conservative Justice
Clinton 0-2-0
0buma 0-2-0
Total: 0-4-0 (0.000)
Which odds do you take?
Check Romney’s judicial appointments in Massataxes, you will find the vast majority are leftists.
First, O’Connor was a Giant Negative, not merely a Zero.
Second, Romney would appoint all O’Connor types.