ST. JOSEPH — Chiefs defensive end Tyson Jackson doesn’t have to look at the stats sheet or study the game tape to determine whether he had a productive game.

He watches how the linebackers behind him fared.

“If Derrick Johnson and Jovan Belcher had a real good game, I know nine times out of 10, I did a good job,” Jackson said of the Chiefs’ two inside linebackers.

“I’ve got to keep those guys free; I’ve got to let those guys run downhill to the ball. I know I’ve had a pretty good game if those guys are satisfied, and we won.”

A year ago, Johnson and Belcher had career seasons, were ranked 1-2 on the team in tackles, and Johnson earned his first Pro Bowl berth. So Jackson must have been doing something right.

But Jackson, the Chiefs’ first-round pick in 2009, is still trying to overcome the label of draft bust ever since his rookie season when general manager Scott Pioli made him the third overall pick in the draft.

To the casual fan, it doesn’t seem like Jackson even gets his uniform dirty. The only names they seem to hear are Johnson … Hali … Belcher … Houston …

“The glamorous part about playing defensive line is getting sacks,” said defensive line coach Anthony Pleasant. “And our defense is a linebacker defense.

“We’re just the grunt guys up front. Our job is to keep the linebackers free to make plays. It’s not a glorified position … if we stop the run, we give them a chance to rush the passer.”

In his three seasons, Jackson has but two sacks in 44 games, but he holds down the left side in the defense, which is critical because most teams are righthanded and direct their running game in that direction.

And according to Pro Football Focus, a website that tracks statistics, Jackson and right end Glenn Dorsey each accounted for more tackles than any 3-4 defensive ends in the NFL, including the Steelers, Ravens and Patriots, who are known for their 3-4 fronts. Jackson was credited with 38 stops on run plays, while Dorsey had 32.

“Tyson is a prototype defensive end you want on the left side,” said Pleasant, who spent most of his 14-year career playing end in that scheme. “He’s got the bulk, he moves well, he can transition from run to pass, so he’s the ideal player you want. A lot of runs go to the left side, so you want someone stout who can defend the run.”

Both Jackson and Dorsey played ends in a 4-3 system at LSU, so it’s taken a while for them to learn the intricacies of the 3-4. Dorsey was the fifth overall pick in 2008, the final year of the Herm Edwards regime, which ran the 4-3. But the Chiefs, in Pioli’s first draft, still took Jackson knowing that he and Dorsey would have to convert to new positions.

It may have taken longer than anticipated for Jackson to fulfill the Chiefs’ hopes, but they haven’t given up on him.

“When you’re picked that high, there’s so much expectation, and some of it is fair and some of it isn’t,” said Chiefs right tackle Eric Winston, who goes against Jackson every day in practice.

“Everybody figures it out at his own pace. Some guys come into this league, and the lucky ones have it figured out … I didn’t. It took me at least a half a year, probably a full year, to really figure out what this league was all about, and from what I heard, Tyson had a pretty good year last year, and you can see he’s building on that.”

When they drafted Jackson, Chiefs officials compared him to former Dallas Cowboys end Russell Maryland, who didn’t roll up a lot of sacks in the Cowboys’ 3-4 scheme but helped win three Super Bowl rings.

“Coming from a 4-3 defense, it’s totally different technique-wise,” Jackson said of his first three years with the Chiefs. “From the outside looking in, it looks like football, but it’s a different type of world …

“I’m starting to pick up things, starting to understand the defense, starting to understand my technique better. I’ve still got some ways to go, but I can see myself getting there.”

So do his teammates. Winston, in his first season with the Chiefs, has been impressed with Jackson’s work ethic.

“The thing I like is he’s working hard, but it’s never enough,” Winston said. “Even when he’s had a couple of good plays, it’s like, ‘Aw, I’ve got to make those faster, I’ve got to get there faster.’ He’s trying to improve his game, and that’s important.

“When you get in year four, year five, it’s easy to say, ‘Well, I’ve probably learned all I’m going to learn …’ He’s realizing there are always things to be learned, always advantages to be had, and that’s been impressive.”

It’s in Jackson’s best interest — as well as the Chiefs’ — for him to have a breakout season this year. During the offseason, Jackson agreed to restructure his contract. His base pay for 2012 dropped from $8 million to $4.25 million with $4 million guaranteed. In exchange, his salary would be $14.72 million in 2013 ($3.2 million guaranteed), so it’s likely that will be restructured again — or Jackson would be let go — depending on how he performs this year.

“I’ve just got to lay it on the line every play,” Jackson said. “Come out there like it’s the last play of my career, so I leave it all on the table and rely on what I’ve been taught over the last couple of years on how to play a 3-4 defense, and how to be strong inside, and how to control those offensive lineman …

“It’s up to us up front to hit those offensive lineman, and keep them flat on the line of scrimmage so the guys in the back can run around and make some plays.”