The Kings were still a bad defensive team last year under Mike Malone and that probably isn't changing any time soon.
When the Kings hired Mike Malone last summer, one of his biggest talking points was about improving the defense. Under Keith Smart, the 2012-13 Kings gave up the most points per game and had the second-worst defensive rating in the entire league. With the team at risk of relocating, defense did not seem to be a priority and Smart instead opted for a fast-pace offense to at least keep it entertaining and work to the team's strengths.
The Kings didn't exactly become a defensive juggernaut in Mike Malone's first year as a coach, but they did get much better. The Kings overall defensive rating improved to 23rd from 29th despite an incredible amount of roster turnover and almost everyone known for defense (Hayes, Salmons, Mbah a Moute) traded throughout the year for offensive minded players.
However, getting better does not mean they became good. The Kings were still one of the worst teams in the league at defending the three point line, ranking 29th in opponent 3 point percentage and opponent shots within 3 feet. They also weren't very good at forcing turnovers, ranking 26th in opponent turnovers per 100 possessions. Sacramento also fouled way too much, ranking 26th in total fouls committed and 27th in opponent free throw attempts. The only areas that the Kings were really above average at defensively was defending the mid-range (3rd at 37.6%) and defensive rebounding rate (3rd).
One thing the Kings did have going for them last season is that they did seem to improve as the season went along. After giving up 46.8%, 47.9% and 46.2% shooting in November, December, and January respectively, the Kings ended the year by holding opponents to 44.8%, 45.5% and 44.6% in the last three months. If they had kept that up all year, they would have been about 9th in opponent FG% rather than 20th.
Sacramento's front office hasn't done much to help Mike Malone improve the defense this summer. The draft yielded Nik Stauskas, a talented shooter and scorer but with a lacking defensive acumen. The Point Guard switch from Isaiah Thomas to Darren Collison has been touted as a potential defensive upgrade, but that could just be a case of switching from terrible defense to just bad defense. Omri Casspi has never been called a defensive stopper and the Kings also lost athletes in Travis Outlaw and Quincy Acy (who might not have been good defenders but at least tried). The one signing that could potentially improve Sacramento's defense is rookie Eric Moreland, but Moreland has a lot of work ahead of him to not only get a rotation spot, but also to make the team itself (terms of his multi-year contract have yet to be disclosed, but it's a good guess that most of it is unguaranteed money).
The Kings are not a team built to be a defensive powerhouse. Barring any other changes, I don't see a whole lot of improvement on this end next season either. DeMarcus Cousins really improved on defense last year and as the leader of the team, he'll have to keep improving. That's why this Team USA experience is so good for him, as he's being asked to take a smaller, more defensive-minded role and he's seemingly responded. It's my hope that both he and Rudy bring that mentality back with them for the regular season.
Sacramento can also help their cause a little bit by improving the offensive efficiency. More made shots and less misses, as well as less turnovers (the Kings were 23rd in turnovers) allows less opportunities for the other team to get fast breaks going before the defense is set.
The Kings will have a full training camp together to get ready and there's unlikely to be the same level of roster turnover that there was last year, so while there probably won't be a huge leap, I do think we'll see additional baby steps taken back toward at least being a competent defensive team. If the Kings can finish this season showing that they can at least be an average defensive team, I think that will be a huge success given the roster makeup, and a good foundation going forward.
(Statistics used in this post courtesy of NBA.com and basketball-reference.com)