While it is true that if you show the pace down, the other team will score fewer points, and vice versa, Fran does NOT need to slow it down a lot, he needs to improve defensive efficiency. That involves a variety of things, but the best place to start is defensive rebounding, limiting second and third chances to score. I am confident that will improve from last year's mess with Patrick, Krikke, and freshmen playing center, but it could get really good with the personnel Fran now has available, if the coaches work at it. The other things, like perimeter players staying in front of their man, learning how to play pick and roll, walling up on the interior without reaching, switching defenses, and constantly communicating with each other, are all things that require repetition and learning to work together. Fran has no excuses to not have a good defense this year. I totally disagree with your position that he can't have good offense and still have a good defense.
You are correct that efficiency, regardless of pace, is what matters. And you are correct that it's completely possible to be good offensively and defensively.
But we're talking about Fran. Nothing has changed in 14 years. Other than he has at times had rosters more capable of defending and rebounding. And this year's team will be one of those rosters if the backcourt stays healthy. The defense and rebounding will definitely be better than last season. But the team will be good at best defensively because Fran will not teach it with the necessary repetition, detail, emphasis, and accountability.
You are correct that extra possessions are huge. Fran does have a team more capable of rebounding and rebounding the way he teaches it.
But to me, the best starting point to improve the D is ball containment. This is easier to fix than all the other stuff, as it only requires effort, emphasis and accountability, and angle detail.
But most importantly, limiting penetration PREVENTS the myriad of other problems that Fran doesn't build his teams to be good at. Poor communication, lack of understanding and executing help rules, lack of personnel appropriate help, over-help, lack of understanding and execution of rotation rules, close-out responsibility and detail, lack of physicality, loss of rebounding position, etc., etc. All of this is prevented by keeping the ball in front of you.
I would call defensive rebounding very valuable, rather than a starting point, as it limits extra possessions. Each possession equates to just over one point on average, depending on how efficient an offense and opposing defense is. But limiting penetration is the starting point, as it allows a defense to keep its rebounding position. And it prevents everything else I mentioned.
But in the end, "starting point" may also be a fairly accurate description for defensive rebounding, as I think it is Fran's main way to address the defense. Rather than put the time in for the necessary repetition and detail-rather than have defense be an emphasis all season, he's gotten some guys that should be able to naturally carve better rebounding position early in the possession. And then hold their positioning for a split-second longer if the D has been broken down, and go and get some boards when they don't have ideal positioning. This team should also get to more lose balls.
As for ball containment, this team has the feet in the backcourt to do it. Unfortunately, it has to stay healthy. And unfortunately, there is no depth to bench someone in the name of accountability. So we'll see how much effort the three guards are able to sustain without being held accountable. This also goes for things like Brock's reach-around. Hopefully he figures out to ditch it, because Fran won't hold him accountable for it. If he does, he will be a great defender.
I anticipate a lineup of something like Thelwell, Dix, Traore, Payton, and Freeman. This team has the feet to keep the ball in front of them, as Traore can guard the 3, which allows Payton to guard the 4. Where the Hawks will run into trouble defensively is if the effort of one of these guys starts to drop, because again, Fran won't hold them accountable for it.
The effectiveness at limiting penetration will drop off a bit as Iowa goes into its bench. At best, Pryce will have to guard some 3's, which at times, will present some problems. Same with lineups that have Payton guarding the 3. And knowing Fran, he will at times play some funky lineups with Payton or Pryce guarding a 2, in which Iowa will be in trouble defensively.
But overall, this team definitely has more potential to defend and rebound. We'll see how much Fran gets out of them in these areas