The Detroit Lions have been much better defensively through four games this season than they were a year ago, but defensive coordinator Aaron Glenn said he came away from his bye week self-scout with one area in particular his group needs to improve. Penalties.

The Lions have been called for 31 penalties through four games, an average of 7.8 per game, eighth most in the NFL.

Rookie Terrion Arnold (eight penalties) is tied for the second-most penalized player in the NFL, behind Houston Texans offensive tackle Laremy Tunsil, and Carlton Davis III (five penalties) is coming off a four-penalty game against the Seattle Seahawks.

Glenn said the Lions worked on reducing penalties in practice this week, but there's a fine line players need to walk in doing so.

"That is a double-edged sword also because along with that I think we’re like second or third in the league as far as pass breakups so that’s something that we’ve emphasized and I’ve wanted here for a long time," Glenn said. "I know a lot of times that can be back and forth because now when you’re not challenging, then you’re playing too soft, when you are challenging, you’re getting those. But the thing is, I’m going to ride with the fact that our guys are out there challenging. We’re going to continue to do what we do."

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Arnold and Davis are the only two defensive regulars with more than one penalty. Marcus Davenport also has two penalties, but is out for the season with a triceps injury, and little-used backup James Houston was flagged twice for offsides against the Seahawks.

Davis said last month he has no intention of changing his physical style of play, while Glenn said Arnold simply needs to be better with some of his technique.

Arnold has been called for at least one pass interference penalty in every game, and three of those flags have sustained scoring drives.

"I don’t know how other teams practice but we still do one-on-ones in practice, receivers (against) DBs, D-line and O-line, linebackers (against) tight ends and running backs," Glenn said. "And when you’re in those situations, man, and you’re in a tussle match, where are your hands at? And a lot of that comes from guys in college, because you’re able to do that when you’re in college. That’s one of the things that T.A.’s doing a really good job of, man, of trying to work on those things and we’ve worked on it first day in practice when we came back and we’re going to continue to work on those things."

Glenn said he won't go to extreme lengths to try and reduce his cornerbacks' penalties, like a coach once did with him and made him practice in oven mitts.

Glenn said he didn't remember what coach did that, but when asked if it was current Dallas Cowboys defensive coordinator Mike Zimmer, who he played for in 2005-06, he said, "it probably was."

"Zim’s my guy, so he probably made me do that," Glenn said. "I love the man as a coach, and one of the reasons why I love him, because he’s demanding, he’s up front, man, but he cares. It’s somewhat similar to (Bill) Belichick. Even though he’s demanding and up front, man, he has a side to him that’s pretty funny and sometimes guys don’t understand that, but I’ve had both of those guys and I love both of those guys."

Dave Birkett will sign copies of his new book, "Detroit Lions: An Illustrated Timeline" at 7 p.m. Saturday at J. Gilligan's Bar & Grill in Arlington, Tx. Order your copy here.

Contact Dave Birkett at dbirkett@freepress.com. Follow him on X and Instagram at @davebirkett.

This article originally appeared on Detroit Free Press: Detroit Lions' Aaron Glenn: Penalties part of having aggressive CBs