“Bush rolled over to Senators Boxer and feinstein and the blue slip method that allowed senators to approve judges for positions in their state.”
No, the GOP leadership of the Senate - 2003 to 2007 did that; that was their doing, and it is one thing the current GOP Senate leader is not doing.
That is not say that all GWBush appointments were good. Roberts was clearly not good.
It is the president who typically continues support or withdraws it as a signal to the senators to move on or not.