The most famous Mike Nolan story, before he became coach of the 49ers, was about vanilla ice cream.

Washington Redskins owner Dan Snyder, the story goes, placed a carton of vanilla ice cream in Nolan's office, where it was allowed to melt into a sticky mess. The mean-spirited prank underscored the owner's criticism of his defensive coordinator's read-and-react philosophy, which Snyder had termed "vanilla."

That story was considered just another in the Snyder-as-meddling-owner file. But it's worth remembering now. Because Nolan's philosophy and his defense's inability to make the big stop and get off the field — all of that is bringing back the images of vanilla ice cream.

When Nolan has been asked this week what's wrong with the defense, he has turned the issue back on his players, using words such as "errors" and "mistakes."

"In the last two weeks, we've made several errors on our own account and have hurt ourselves," Nolan said. "Some have been technique, some have been mental."

None, though, apparently have been scheme or coaching. In another comment Monday, Nolan said it didn't matter how well something was drawn up on the chalkboard, it comes down to execution.

But questions about Nolan's philosophy have followed him for years, through his stints in the NFC East, first in New York and then in Washington. A decade ago, Redskins players grew frustrated under Nolan's direction. After being singled out by Snyder, Nolan vowed to become more aggressive, and defensive players wore shirts that read "Relentless. Attack. Physical." But after the 1999 season, when his defense finished at the bottom of the league, Nolan was fired, and the complaints about his passive system went public.

We're starting to hear some of the same grumblings about read-and-react around the 49ers. Though the 49ers did blitz about a third of the time against New England, they often were burned badly by Matt Cassel when they did. And some of the key gains for the Patriots — such as the play that put them in range for the clinching field goal — came when the 49ers were less aggressive.

Damned if you do, damned if you don't?

The defensive letdowns are problematic for Nolan. Although he has a defensive coordinator in Greg Manusky, it's clear that this defense is Nolan's baby. Nolan has completely turned the offense over to Mike Martz and while that unit has its problems, it has been more entertaining than in recent years. Nolan's defense is the bigger problem and that reflects poorly on a coach already under fire.

Wednesday, a couple of the 49ers who used to play in Philadelphia — safety Michael Lewis and linebacker Takeo Spikes — talked about playing under aggressive Eagles defensive coordinator Jim Johnson.

"That's his mentality," Spikes said. "It was a fun scheme, a scheme that I liked. You're in the attack mode all the time."

Lewis also loved the system that turns players loose, saying, "It's very aggressive. You never know where it's coming from. He's not afraid to put nine guys in the box."

When asked if the 49ers need to be more aggressive, Spikes said he thought they had a good mixture of approaches.

"It's all about what you're accustomed to running," he said. "These are two totally different mindsets. At the same time, it's personnel and what you draft people to come in and do."

Spikes was asked if he thought the 49ers' defense had an identity.

"I think we have an ID, but it's not consistent," he said.

And what is it?

"Make plays. Force turnovers."

The 49ers — tied for 21st in defense and ranked 23rd against the run — are tied with several other teams for seventh in the league in forcing turnovers. But right now the 49ers aren't making plays.

Whatever their identity is, it's very non-threatening. After five games, some might even call it vanilla.