"She liked his quiet confidence; he didn't seem to be pushing too hard for the job."

Jan Crawford Greenburg tells the story of George Bush's Supreme Court appointments. Here's the part about Samuel Alito:

The call from the White House surprised Alito. Living in New Jersey, he had been insulated from the negative Washington buzz over Miers. He had absorbed the disappointment about being passed over and had come to terms with remaining a federal appellate judge. Alito didn't know that he had been Miers's choice for the O'Connor vacancy after Roberts got the nod for the top spot. She liked his quiet confidence; he didn't seem to be pushing too hard for the job. When Alito was nominated just four days after Miers dropped out, she greeted him warmly in the White House, moments before Bush introduced him as his next nominee.

Note the implication: Others lost favor by pushing too hard.

And here's Greenburg's conclusion:

Bush fulfilled his early vow to appoint justices in the mold of Scalia and Thomas. Together with those two justices, Alito and Roberts make the Roberts Court the most conservative Supreme Court in half a century. Roberts and Alito will not be as forceful as Scalia and Thomas on the bench or in their opinions; they are unlikely to push moderates away with their strong views. For that reason, they may be more effective than Scalia or Thomas in finally removing the court from the contentious social issues that conservatives think belong in legislatures. With the court now poised to recede from some of those divisive cultural debates, George W. Bush and his lawyers at the White House and Justice Department will continue shaping the direction of U.S. law and culture long after many of them are dead.

So, that seems to say, if there's any moderation in Roberts and Alito, it serves the function of making their conservatism more effective.