Zombo has spent each game near outside linebackers coach Kevin Greene in the Packers' bench area, dissecting plays and taking notes on what Matthews and fellow starter Erik Walden do.
And Zombo understands how surprising it seems that Matthews has had just one sack so far after getting 23.5 over his first two NFL seasons. He believes the sack number doesn't measure Matthews' full impact.
"Clay's disrupting plays all over the place," Zombo said Thursday, as the Packers prepared for Sunday night's game against the Atlanta Falcons.
"He's getting a lot of criticism right now or whatever because he only has one sack, but you have a guy like that taking up three blocks and still getting quarterback hits, that's obviously taking away from the offensive line and allowing other guys to make plays and helping our defense win."
Matthews said last week he wasn't concerned about his limited statistical productivity.
"Sacks are a very misleading statistic. Obviously, I had six after two games last year," Matthews said.
"I'm doing my job, which is to put pressure on the quarterback. There's no doubt about that. And I'll be here when they're ready to come my way.
"That's why I laugh at it because people want to jump in and say I haven't gotten the sacks, but at the same time, as long as I'm making impact plays, whether that be in the run game or pass game or covering someone, then I'm doing my job."
The Packers are tied for eighth in the NFL with 11 sacks, four sacks behind league-leading Washington and Philadelphia.
Green Bay finished with 37 sacks in 2009 and 47 in 2010.
Packers coach Mike McCarthy has been impressed with Matthews' play.
He was involved in the goal-line stand that preserved the Packers' opening-night win over New Orleans.
He made a key fourth-down stop on a fourth-quarter scramble inside the 5-yard line by Carolina quarterback Cam Newton in Week 2.
He was key in slowing down Chicago running back Matt Forte in Week 3.
In addition, Matthews leads the team in quarterback hits with 18.
"There are other factors involved," McCarthy said.
"There's nothing wrong with the way Clay Matthews is rushing the quarterback. It's defense. It works together. The rush has to fit together with the coverage, and usually when the coverage holds longer, it creates more opportunities for more pressure from your pressure players up front.
"Clay's having a very good year. He really is. I understand the statistical analysis of one sack."
Matthews' sack total aren't the only numbers that are down on the Packers' defense.
While the Packers (4-0) are off to their best start since 2007, they rank 28th in total defense and 31st in pass defense entering Sunday night's game.
In their first two seasons under veteran defensive coordinator Dom Capers, they ranked in the top five in total defense each year, finishing No. 2 in 2009 and No. 5 last year.
Their saving grace defensively has been forcing turnovers, as the Packers are tied for the NFL lead in interceptions (eight) and tied for second in total takeaways with 11.
Asked earlier this week if Matthews' quadriceps injury might be a factor, McCarthy didn't dismiss the notion.
Last season, Matthews played the second half of the season with what turned out to be a stress fracture in his shin, an injury that limited him in practice each week.
On Thursday, Matthews sat out his second straight day of practice, although he's expected to practice Friday.
"When you're injured as a player, I don't care who you are, and you don't practice, it may not directly affect you as far as your performance, but the continuity that comes along with practice is important," McCarthy said.
"So, is that a factor? No excuses, we're not going to make any. We did that better than anybody in my opinion last year, overcoming injuries."
McCarthy also said Thursday that the Packers' defensive approach has played a role, saying, "Are we rushing three more than we have in the past? Four? Five? Those are some things you need to look at."
"Clay is having another fine year. He's doing everything we're asking him to do," Greene said. "Very rarely will he have a one-on-one. I see him getting two if not three guys.
"Clay knows he's on the radar now. He just needs to keep doing what he's doing. He's playing physical and doing the right things. Other people are making plays because of Clay's getting (double-teamed). He's absolutely tracking. I couldn't ask for more of Clay's progression."
Follow Associated Press writer Chris Jenkins on Twitter at twitter.com/ByChrisJenkins.