As always, I'm a fan of using more data. We're looking at a very small sample size here and it's hard to make very definitive statements. What if we take all teams in the league over the past five years?
It's impossible to break it down into wins/losses easily when you look at this data, but what is just as good is to look at a team's winning percentage. Thus, rather than ask how a team did in a win, versus how a team did in a loss, just ask what was a team's winning percentage for the entire season, and then compare that to their performance in these categories to see where there are correlations and where there are not.
I made the plots for all of these, but I will spare everybody the eyesore and simply report the results, as everything is relatively straightforward. One caveat to note is that for all comparisons, instead of using winning percentage (as I said just in the paragraph above) I am instead using Margin Of Victory as a proxy for winning percentage. It has been shown repeatedly (and I have in the past independently verified) that MOV is a very, very good proxy for winning percentage over the course of a season (we're talking like explaining well over 90% of the variance), and MOV is a simple cut-and-paste from basketball-reference.com while winning percentage is not. That's the only reason I did it. I have no doubt whatsoever that using actual season winning percentages would not change any of the conclusions below.
Part I -- What Does NOT Matter
1) Pace. Pace? PACE.
Kings Pace in 16 wins: 93.74
Kings Pace in 21 losses: 93.76
The relationship between MOV and Pace is absolutely flat. No correlation at all.
Verified: Pace does not matter.
2) Assists. Do NOT Matter.
Kings Assists in 16 wins: 19.4
Kings Assists in 21 losses: 20.0
Raw assists is not the best number to use here because it's not pace-independent. b-r.com doesn't have a simple assist rate column for its team stats, so I cobbled together my own crude approximation: Ast/FGM. This is %age of made baskets assisted, which is really what we're asking anyway. There is a very weak positive relationship (r = 0.14) that is not quite statistically significant.
Mostly Verified: There appears to be a very small positive effect of additional assists, but the relationship is very noisy.
3) Three Point Shooting. Does NOT matter.
Kings Three Points Makes/Takes in 16 wins: 4.9/14.3
Kings Three Points Makes/Takes in 21 losses: 5.7/16.5
And on that latter the gap is big enough you could almost argue for a NEGATIVE correlation. I.e. the more threes we shoot, the more we lose.
One problem with the split by wins/losses approach is evident here, because strategy may change depending on game situation. For instance, it is possible that a team that is losing late (and therefore likely to lose) will jack up more threes in an attempt to catch up. Here I simply used 3pt rate against MOV. There is a good, statistically significant (p = 1x10^-4, r = 0.31) positive relationship between three point rate and MOV. Note that this does not even take into account three point percentage.
Falsified: There is a positive relationship between three point rate and winning percentage.
Part II -- What DOES Matter
1) Free Throws
Kings Free Throw Makes/Takes in 16 wins: 26.8/33.0
Kings Free Throw Makes/Takes in 21 losses: 20.9/28.1
Here I used free throw rate, which is a decent measure of how often a team gets to the line. One caveat here is that strategy does potentially play into this one: teams that are winning down the stretch tend to get fouled intentionally and that could explain some of the correlation here. There is a fairly good, positive relationship between free throw rate and MOV (p = 0.014, r = 0.2) which is statistically significant depending on choice of criterion.
Mostly Verified: There is a small positive relationship between free throw rate and winning percentage.
2) Turnovers
Kings Turnovers in 16 wins: 13.9
Kings Turnovers in 21 losses: 16.7
Here I used turnover percentage. The relationship is almost exactly as good as that between free throw rate and MOV (p = 0.010, r = -0.21). Since turnovers are something you want to avoid, the negative sign is expected.
Mostly Verified: There is a small negative relationship between turnover percentage and winning percentage.
3) Defense, in ALL its particulars
Kings Defensive Stats in 16 wins: OppFG: .412, Opp3pt%: .294, Steals: 7.1, Blocks: 4.6
Kings Defensive Stats in 21 losses: OppFG: .476, Opp3pt%: .357, Steals: 6.0, Blocks: 3.6
Here's the doozy. Probably the best stat to use is DRtg, which is an approximation of how many points you give up per 100 possessions. There is an extremely strong correlation between DRtg and MOV, with an r of -0.72 and a p-value around 10^-25. This is a far stronger relationship than any other we've looked at so far.
Totally Verified: Defense matters a LOT.
However, there is one thing that Brick didn't look at, which is offense. Does offense matter as much as defense? It's as simple as doing the same calculation for ORtg as we did for DRtg. The relationship for offense turns out to be marginally stronger than the relationship for defense (r = 0.77, p = 1x10^-30). Does that mean that offense is MORE important than defense? Or is the relationship so strong for each that the differences between them are insignificant? You guys can fight that one out.
Bottom Line: Offensive efficiency matters no less than defensive efficiency.
Essentially, what these numbers say is that following: Make your defense as efficient as you can make it, make your offense as efficient as you can make it, and nothing else really matters. There are a few ways to make your offense better: Taking more threes helps your offense by a good amount. Committing fewer turnovers helps your offense a bit. Getting to the free throw line helps your offense a bit. And moving the ball might help a little. But how fast you play appears to make not a whit of difference in your ultimate success.