Their weakness is growing muscles. Their sore spot is starting to heal. The aspect that once did them in is now bailing them out.
The Raiders, after many years of shame and despair, are building an actual defense.
Evident once again in a 26-16 win over Kansas City on Sunday at Arrowhead Stadium is that Oakland's retooled defense is neither dominating nor suffocating. But it is becoming quite competent, and it's developing the discipline that long has been missing.
Moreover, this Raiders "D," which has shown noticeable improvement since the bye week, has the capacity to get appreciably better.
This unit clearly understands the three keys to good defense in the NFL are containing the stars, stopping the run and getting turnovers. The Raiders did all three against the Chiefs who, to be fair, might be the worst squad they will see.
Four Kansas City turnovers, three generated by the defense, led directly to 13 Oakland points. Kansas City has two truly dangerous players, and the Raiders stifled both. Running back Jamaal Charles gained 4 yards on five carries and 6 yards on three catches. Wide receiver Dwayne Bowe was held to three catches for 65 yards.
"We focused on (Charles) and No. 82 (Bowe)," outside linebacker Philip Wheeler told reporters afterward. "We felt like we did a good job on (Charles). We rushed the quarterback pretty well. We just got after people."
Amid widespread criticism directed, justifiably, at Oakland's offense -- curious play-calls, frustrations while implementing the zone-blocking system, interceptions thrown by quarterback Carson Palmer -- the defense now is playing solidly, as well as it has since 2002.
Considering the circumstances under which coordinator Jason Tarver's unit has performed, it has been downright terrific.
Neither starting cornerback, Ron Bartell nor Shawntae Spencer, has played since Week 2. In their places are a backup, Pat Lee, who is improving each week, and career-long safety Michael Huff, who has gotten more and more comfortable at the corner.
It's as makeshift as it gets, sheer improvisation out of necessity.
But even as the defense evolves and adds more exotic schemes, there's constant personnel evaluation.
Accepting the limitations of middle linebacker Rolando McClain, who tends to play the run poorly and the pass worse, coach Dennis Allen and Tarver have made him more of a situational player while giving more responsibility to productive rookie Miles Burris.
Meanwhile, Wheeler, signed as a free agent from Indianapolis, has proved too dynamic, too steady and too valuable to come off the field.
Led by Wheeler and Burris and third-year defensive end Lamarr Houston (reigning AFC Defensive Player of the Week), the defensive unit also has raised the consistency of its effort. These three, in particular, seem to play every down in overdrive.
It seems to be paying off. Since being humiliated by Miami running back Reggie Bush (172 yards) in Week 2 and by Denver's Willis McGahee (112) in Week 4, the Raiders have been stout against opposing runners -- especially the primary backs.
Charles got nothing Sunday, one week after Jacksonville's Maurice Jones-Drew and Rashad Jennings combined for 50 yards on 23 carries. One week before that, Atlanta's Michael Turner managed only 33 yards.
"Those guys (defensive coaches) are really doing a good job of figuring out what the other team is going to be doing," backup safety Mike Mitchell said. "We're just playing physical. We're finally understanding each other."
The Raiders finally might have solved the problem that has vexed them for the last nine seasons, all of which ended with their run defense ranked in the NFL's bottom 10.
They entered this game ranked 13th in the league against the run, allowing the same 3.8 yards per carry as the heralded 49ers run defense. Only six teams have been stingier. Four Kansas City running backs gained a total of 49 yards on 13 carries.
Said Allen: "Our guys up front, our linebackers and defensive linemen did an outstanding job of using their hands to get off blocks and make some plays and limit them as far as the run game is concerned."
Yes, Kansas City likely is the most predictable win on Oakland's schedule. What once was a rivalry has become too one-sided, with the Raiders winning seven of the last 10 and six in a row at Arrowhead.
And even after Darren McFadden rambled for 114 yards Sunday, the offense continues to seek both consistency and an identity, But the defense, even after collapses in Miami and Denver, seems intent on shedding its image of giving away games and being The Reason for so many close losses.
It took years to earn the reputation. It's going to take many more games like these last three for it to disappear. If you look closely, though, it appears the old image is starting to fade.