North Texas coach Dan McCarney watched his young defensive secondary, with little to no college experience, grow into a cohesive unit last year and in the spring.“I smile right now when I start talking about my secondary,” McCarney said before the season.He wasn’t all smiles this week, though, when asked to grade the performance of the unit that has played inconsistently and shown a vulnerability to the big play.Senior Hilbert Jackson and sophomore Zac Whitfield have both given up long pass plays early in games.Whitfield, who switched from running back a season ago, was victimized by Chase Cochran’s 75-yard touchdown reception from Tyler Tettleton on the first play of last week’s 27-21 loss to Ohio on the road.Tettleton was 19-for-30 for 239 yards and two touchdowns. In the season opener, Idaho’s Chad Chalich was 19-for-27 for 230 yards, including a 59-yard completion on the Vandals’ first possession.The task Saturday is no easier for North Texas (1-1), which is trying to go 2-0 at home for the first time since 2003. Ball State is in Denton for a 3 p.m. kickoff boasting a high-octane attack. Senior quarterback Keith Wenning, 13th in the nation in passing yards, and his teammates have scored an average of 45.5 points per game in blowout victories over Illinois State and Army.“It sucks the life out of you, whether you’re at home or away,” said McCarney about last week’s big play. “We have to stop that. It’s inexcusable.“You make your job harder when you make those kind of mistakes.”Much of McCarney’s critique centered on Whitfield, one of only nine freshmen in the nation with three or more interceptions in 2012. He also had a Sun Belt-leading 12 pass breakups.Starting this week at that spot will be Kenny Buyers, who along with Marcus Trice, had an interception last week.“We’re not going to stand around and watch guys in position to make plays and not make them,” McCarney said. “I’ve seen Zac Whitfield make that play in practice and scrimmages. You have to carry it over to game day. “We’re all measured on Saturdays. Not Monday through Friday.”The unit as a whole needs to be more consistent, said McCarney who loaded praise on Trice, a Mean Green safety whom the coach called “outstanding” in the first two games.New return policyNot many FBS schools were worse in the punt return game last season than the Mean Green.Those problems appear to be lost to the past.Brelan Chancellor leads the nation in punt returns, averaging 34.5 yards per return. On four returns, he has 138 yards.That total is more than North Texas compiled in the last three seasons combined over 36 games, including 17 yards in all of 2013.