NASHVILLE -- The Tennessee Titans head into the regular season -- their first under the guidance of Ken Whisenhunt -- with some questions still to be answered.

First and foremost on the list of questions is the Titans defense, which is switching from a 4-3 system that has been in place ever since the franchise arrived here in 1997, to a 3-4 under Ray Horton.

The transition, at least from the evidence shown in preseason, has not been altogether smooth. In each of Tennessee's four preseason games, the Titans surrendered a touchdown drive on the opening defensive series.

In fairness, the Titans' second-team defense played in the preseason finale against Minnesota, and there is always the old fallback of not game-planning for a preseason opponent, but there was enough of a concern over a lack of a pass rush and an inability to get off the field on third down, combine with missed tackles, that led Whisenhunt to deliver a halftime tongue-lashing to his defense in the so-called dress rehearsal game against Atlanta in preseason week three.

"I've seen a lot of teams that don't have stats in preseason that end up being good teams that have good stats in-season," Whisenhunt said. "I'm not saying that's a predictor one way or another, but I think there are a lot of snaps that aren't in preseason games that you can help formulate an opinion about your defense, as far as what you're seeing from them in practice and competition against them, offensively and defensively.

"There are a lot of things that we did in practice that we didn't do in preseason games. Some of the things in preseason games are geared towards individual matchups, so you can see how your players stack up as opposed to a scheme where you're attacking a particular protection or you're attacking the way that an offense runs. From that standpoint, we feel like our guys have worked hard, and they're prepared. Hopefully that will be reflected in the way we play against Kansas City."

Perhaps, because the Titans still have plenty of other issues as well.

They still don't know who will kick, whether it will be Maikon Bonani, who struggled in the preseason with inconsistency, rookie Travis Coons, who has not demonstrated sufficient leg strength on kickoffs, or a player plucked from waivers or the street.

"We feel comfortable with both of those guys. I think we are looking at all opportunities which is what you should do. It is the smart thing to do, but we certainly feel comfortable with those guys," Whisenhunt said.

Amazingly, the offense, which may have been the biggest question mark coming into the season, given the health of Jake Locker and questions about whether he would fit Whisenhunt's offense, has been the strongest unit on the team in preseason.

Locker has looked solid in both his throws and decision-making, and if young wideouts Kendall Wright and Justin Hunter continue to develop, the offense could be the most improved part of the 2014 Titans.

NOTES: DE Jurrell Casey signed a four-year, $36 million extension on Wednesday, with $20.5 million guaranteed, assuring that he will be a part of the Titans defensive plans for some time to come. He had 10.5 sacks a year ago. ... WR/KR Marc Mariani was released as he was trying to make a comeback after two years on injured reserve. Mariani lost the return job to Leon Washington and Dexter McCluster and could not unseat Michael Preston and Derek Hagan as a wideout. ... CB Tommie Campbell's struggles against the Vikings in the preseason finale -- three penalties and a TD given up -- led to his release. ... FB Collin Mooney was released, but might be re-signed to the practice squad if he clears waivers. He was Tennessee's primary fullback last year, but the Titans moved Jackie Battle into that role this year. ... RB Antonio Andrews was let go despite a strong preseason and the team may try to sneak him back onto the practice squad. ... QB Zach Mettenberger led the NFL in passing yards in the preseason, showing a strong arm and good decision-making. But for now, he goes back to being a third-stringer behind Jake Locker and Charlie Whisenhunt.