The Detroit Lions made three large investments in their defensive line before the season. So far, none has paid off.

Mike Daniels, who signed a one-year deal worth about $8 million in July, has played sparingly because of a foot injury he suffered in a Week 3 win over the Philadelphia Eagles.

Damon Harrison, who got a $2 million raise this fall as part of the one-year extension he signed in August, said Monday that his struggles have contributed to the Lions’ overall failings against the run.

And Trey Flowers, who signed a five-year deal worth up to $90 million in free agency, has one sack in the Lions’ 2-3-1 start.

Flowers never has been a big sack producer in college or the pros, and while the Lions expected more than he’s provided in that department, they felt comfortable giving him one of the richest defensive contracts in NFL history because of the way he affects games beyond the pass rush.

With that in mind, I decided to put Flowers’ play under the microscope in this week’s film review to see if his contributions go beyond his rather ordinary stat line. He showed some rust early this season as he returned from February shoulder surgery — he did not play in the preseason — and made effective plays against the Eagles (when he had eight tackles and his only sack) and Chiefs (when he forced a fumble in Kansas City territory).

With a bye week after the Kansas City game, I decided to use that as a line of demarcation of sorts and review every snap Flowers played the last two weeks in losses to the Green Bay Packers and Minnesota Vikings, two NFC North foes he’ll face again.

Flowers played 85 total snaps in those two games and was credited with seven tackles (two of them solo) and nothing else. No quarterback hits, no forced fumbles, no deflected passes. Nothing.

In Green Bay, he played primarily against David Bakhtiari, one of the NFL’s premier left tackles. Last week, he faced ex-Lion Riley Reiff, a league-average edge protector who had an excellent game.

Before jumping into the review, it’s important to understand how the Lions use Flowers, who’s played primarily as the team’s right defensive end this year but gives way to Romeo Okwara for a few series a game.

When the Lions give one of their pass rushers a series, they tend to keep them on the field for the entire drive, whether that’s three plays or 15 (as was the case in Minnesota’s 97-yard touchdown drive last week, when Flowers was on the bench). In both games I studied, Flowers did play in obvious third-down pass-rush situations even on Okwara’s drives.

Green Bay Packers

Flowers played exclusively on the right side of the defensive line this game, with four of his snaps coming from what was essentially the right defensive tackle spot and the rest at right end. He played a variety of techniques out of the end spot, from split wide of the left tackle to inside lined up over the left guard.

No matter where he played, Flowers had little impact on the game.

Of the 51 snaps Flowers played against the Packers, 30 were pass plays, and he appeared to have pass-rushing responsibilities on 27 of those snaps. (The other three were screen passes, play-action plays or run-pass options in which he had contain duties.)

By my count, Flowers got late pressure — after Aaron Rodgers held the ball for more than 3.5 seconds — on three of those snaps and true play-impacting pressure on none. Whether he lined up against Bakhtiari, rookie left guard Elgton Jenkins or a tight end (as he did once), he was a non-factor as a pass rusher.

Flowers was called for one of his two questionable hands-to-the-face penalties on one of his late-pressure plays, and he faced double- or triple-team blocks on seven of his pass-rush snaps. The Lions did not do him any favors by anchoring him to the right side of the line, and their frequent three-man rushes allowed the Packers to send extra help Flowers’ way.

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All three of Flowers’ tackles came on running plays. I thought he deserved a fourth tackle for an assist on a fourth-quarter run with about two minutes to play, when he slid down the line to help stop Jamaal Williams. But one of his tackles was a gift, when Williams slid before the goal line as the Lions were attempting to let the Packers score a touchdown at the end of the game.

On another one of his tackles, Flowers did a good job two-gapping on a play run directly at him, though Aaron Jones ran into Bakhtiari’s backside — Flowers was one-on-one with Jenkins on the play — and Flowers was credited with the stop.

Minnesota Vikings

Flowers played 34 snaps against the Vikings, and 18 of those came on pass plays. Because the Vikings used so much play-action, it’s hard to know what Flowers’ responsibilities were on his way to the quarterback. Regardless, I didn’t chart him with a single pressure in the game.

The Lions did move Flowers around some against the Vikings, but their rush plan was easy to track. Flowers played as the left defensive end on four third-and-long situations, and the right defensive end spot — again, out of various techniques — on every other play.

Reiff largely had his way with Flowers, but he wasn’t without help. The Vikings double-teamed Flowers on five passing plays (and one run), and largely stayed away from him in the running game.

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Flowers did make four tackles against the Vikings. He shed a block to assist on a tackle in the first quarter and fought off a Reiff block trip up Dalvin Cook on Minnesota’s first play of the third quarter.

For the most part, Flowers is an effective run defender, though he did take one false step inside when Cook beat him to the edge for a 23-yard gain on third-and-1 in the fourth quarter.

Overall

Flowers is a solid run defender who can two-gap when plays are run his way and rarely gets taken to the ground. He’s a high-effort pass rusher, but at least in the past two weeks, he hasn’t been able to win with his moves.

The Lions share in the blame for Flowers’ lack of production as they’ve given him little help getting to the quarterback. I counted one stunt he ran with another defensive lineman in nearly 50 pass plays, and I wonder if keeping Flowers (or Okwara, for that matter) on the field for every snap of a long drive is in their best interest, or if it’d be better to keep their legs fresh with a short break.

Asking Flowers to consistently beat good tackles with a long-arm or bull-rush is a losing proposition, especially when help awaits in the form of other blockers because the Lions rush so few defenders. Flowers did not make any true impact plays (outside of the controversial penalties) the last two weeks, so much of the criticism directed his way is deserved. A lot of it, of course, is related to the contract he signed.

But watching the film, I was reminded of something Flowers said after Sunday’s loss to the Vikings when asked about the Lions’ feeble pass rush as a whole.

“Today it wasn’t a lot of opportunities 'cause like I said, we didn’t stop the run,” Flowers said. “Anytime you don’t stop the run and they’re running a lot of play action, it’s like, we come, we play, we try to stop the run, stop the run, but now it’s a play-action pass and it’s tough to get there. Obviously, it’s still our job to get there, but I think you’ve got to start off by stopping the run and that’s one of the big things we got to fix. We got to earn opportunities to rush the passer.”

The Lions haven’t earned those opportunities yet, and until they do, Flowers will keep drawing criticism.

Contact Dave Birkett at dbirkett@freepress.com. Follow him on Twitter @davebirkett. Read more on the Detroit Lions and sign up for our Lions newsletter.