Last week, as one of the best tight ends in NFL history studied the 49ers’ offense, he kept noticing their young tight end.

And Jason Witten became extremely intrigued by George Kittle.

After poring over video of Kittle’s 2018 season, ESPN’s rookie “Monday Night Football” analyst reviewed part of his 2017 rookie year.

Finally, Witten — both impressed and perplexed — broadened his “deep dive” on Kittle by watching some of his senior season at Iowa.

“I went back to watch some of his college tape,” Witten said, “because I was thinking, ‘Man, how did this guy fall to the fifth round?’”

Kittle, the ninth tight end drafted in 2017, soon could be mentioned in the same breath as the top players at his position. At least that’s the opinion of Witten, 36, who ranks fourth in NFL history in receptions — No. 2 among tight ends — after finishing a 15-year career with the Cowboys last season that included 11 Pro Bowls.

Witten’s pregame study has made him eager to see Kittle firsthand when the 49ers visit Green Bay on Monday night. In fact, Witten had planned to seek out Kittle for a chat Sunday when ESPN’s crew met with some of the 49ers’ coaches and players.

49ers (1-4) at Packers (2-2-1) When: 5:15 p.m. MondayTV:Channel: 7ESPN, ESPN2Radio: 680, 107.7 Spotlight on: LT Joe Staley: After he had what he deemed a poor performance against the Cardinals while playing with an injured right knee Oct. 7, Staley said Friday his knee felt more stable as he prepared to face a familiar foe: Green Bay outside linebacker Clay Matthews. The Pro Bowlers have faced each other in five games during their careers and Staley said he reviewed those matchups in advance of their coming meeting. Matthews has just half a sack this season, with two more apparent sacks negated by questionable roughing-the-passer penalties. “The first time I played against him, I was taken aback by just how strong he is,” Staley said. “… And he’s a smart player, too. He’s pretty crafty. He can give a look like he’s going to do a bull-rush and then he’ll give you something off that.” Injuries: 49ers — WR Trent Taylor (back) is doubtful; RB Matt Breida (ankle) and WR Pierre Garcon (shoulder, knee) are among seven players listed as questionable. Packers — WRs Randall Cobb (hamstring) and Geronimo Allison (hamstring) are questionable after missing the previous two games. What to watch for The Packers have a .727 winning percentage (71-26-2) at home since 2006, which is the third best in the NFL over that span. In their past 28 games that QB Jimmy Garoppolo hasn’t started, the 49ers are 2-26. The 49ers have won eight straight on “Monday Night Football,” and their 48 wins are tied for the most in NFL history with the Cowboys and Steelers. — Eric Branch Monday’s game Who: 49ers (1-4) at Green Bay (2-2-1) When: 5:15 p.m. TV:Channel: 7ESPN, ESPN2 Radio: 680, 107.7

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“I think, ability-wise, yes, (Kittle) can be in that future batch — you’re throwing him in with some of the best ones: (Philadelphia’s) Zach Ertz, (Kansas City’s) Travis Kelce and (New England’s Rob) Gronkowski,” Witten said. “He really reminds me a lot of (Carolina’s) Greg Olsen.”

Considering the four tight ends Witten mentioned have combined for 12 Pro Bowl berths, that’s high praise for a No. 146 pick who has played in 20 NFL games.

Kittle has earned it with a breakout 2018 in which he has been one of the few bright spots on a 1-4 team. Kittle who has 23 catches, entered Sunday ranked third — behind Ertz and Kelce — among tight ends in receiving yards (399) and eighth in the NFL in yards per catch (17.3). He’s on pace for a 1,277-yard season that would shatter Vernon Davis’ team record (965) for yards by a tight end. And Kittle has set the record for the longest touchdown catch (82 yards) by a tight end in franchise history.

About those eight tight ends drafted ahead of him: They had an average combined stat line of seven catches for 87 yards this season entering Week 6.

As Witten quickly discovered, Kittle has moved to the head of a class that was headlined by Tampa Bay’s O.J. Howard, the No. 19 pick last year.

“I started watching early on and (No.) 85 just kept popping up,” Witten said. “I was just like, man, this Kittle.”

Witten knew about Kittle’s impressive statistics this season, but he wondered if they were a product of Kittle serving as one of the few decent options on an injury-thinned offense.

Witten didn’t develop an appreciation for Kittle’s all-around skills until starting his pregame homework. During a 15-minute phone interview, Witten spent the first five minutes discussing Kittle’s run-blocking.

Witten was struck by his willingness and aggressiveness in the trenches, but also his feel.

For example, when Kittle stays in to block on play-action passes, he’s often responsible for an area instead of a specific defender. Witten noticed how Kittle instinctively vacates his spot to pick off free pass rushers. It’s an awareness that extends to his higher-profile work as a receiver.

“He’s very athletic, but the No. 1 thing that sticks out to me is that he’s instinctive and has a really good feel for the field,” Witten said. “Not just in the passing game and running routes — an overall feel and awareness. And that’s the No. 1 trait of a tight end. ‘Why did you turn in when you had that option route and not turn out? Something told me to turn in.’ And he has that. ...

“He has the ability to play (backyard) ball sometimes. Not to run it just like (head coach Kyle Shanahan’s) PowerPoint says to run it, but you’ve got to have a little bit of feel in there. That’s what impressed me the most.”

Kittle’s comfort in Shanahan’s complex system has allowed him to combine his instincts with his athletic ability. This season, a year after he had 43 catches for 515 yards, he credits his improvement to the fact that his “head’s not cut off running around and not knowing what’s going on.”

As a rookie, Kittle left the huddle focused on his assignment. This season, he has come to the line of scrimmage focused on the defense’s alignment.

“It’s not ‘What’s my job?’” Kittle said. “It’s ‘How do I make my job easier this play?’”

At the 2017 combine, Kittle had the third-fastest 40-yard dash time (4.52 seconds) among tight ends. And his wheels were on display on his 82-yard touchdown in Week 4 when he outran three Chargers for the final 60 yards.

Kittle guessed it might have been his longest catch since junior high. It certainly didn’t happen at Iowa, where he wasn’t featured in the passing game and had 48 catches in four seasons .

His lack of involvement as a receiver, coupled with a senior season in which he missed four games with lower-leg injuries, explains last year’s tumble to the fifth round. Shanahan has repeatedly said he was surprised Kittle was available so late, but Kittle said he hasn’t been motivated by any draft-snub anger.

“No,” he said. “I’m just happy I got drafted, honestly.”

Kittle isn’t looking back, but ahead to his next game.

On Friday, when he was told about some of Witten’s praise, Kittle smiled and said he studied video of Witten throughout college.

“Anytime you can make an impression on someone that’s done it for years and has always been great, that’s awesome,” Kittle said. “... I hope I can prove him right Monday.”

Eric Branch is a San Francisco Chronicle staff writer. Email: ebranch@sfchronicle.com Twitter: @Eric_Branch