I do think the opposing lineup matters. While the Phoenix bench may be better than the starters, at times, I don't think many benches in the NBA are ever better than the Suns. If the Suns bench is playing a weak bench, they're going to blow them away.

It'll be interesting to see if we see Dragic and Nash on the floor at the same time more often next season.

By the way, love the site and the work you've put into i.

However, this discussion isn't really relevant to lineups, because 5-man units have a much lower standard error in their +/- estimates. Joe Sill's work was with predicting out of sample 5-man performance from individual +/- ratings, but the 5-man scores I listed above derive from data on that lineup as a unit, indivisible into smaller parts. Which is why right now, you can say with a lot more confidence that "Lineup X is better than Lineup Y" than "Player X is better than Player Y" using +/-.

I guess I'm still of the mindset that while these stats are definitely interesting, their best use is not to determine what lineup should be played regardless of the opposing lineup. I think the matchups plays a bigger part than what is showing up in the stat tables.

http://sloansportsconference.com/uploadfiles/pdf/joeSillSloanSportsPaperWithLogo.pdf

http://www.hoopnumbers.com/allAnalysisView?analysis=RAPM&discussion=True

But I think you may be misinterpreting what I mean when I say it takes into account the opposing lineup strength -- I mean that the raw net +/- of a lineup is autmomatically adjusted based on the opposing lineup during each of its "shifts", so a lineup that faced nothing but bench players would not have an APM as good as its net +/- would have you believe. In other words, the level of competition adjustment is built into the regression.

Even if two lineups have never faced, we can predict their performance against each other based on how they've each performed vs. common opponents -- it's essentially like those college football rating systems that determine the relative strengths of Alabama and USC even though they've never faced each other, because they have common opponents, or their opponents have common opponents, etc. Every unit is connected to every other unit somehow; the units that are more well-connected have smaller standard errors because we're more confident about their "true" skill level.

In fact, in Game 4's zone extravaganza, those two were never on the floor together. Same (minus garbage time) with Game 3's win. I think the Last 10 Games link you posted only had the San Antonio and Portland series data skewing the results, because aside from some garbage time in Game 2 that combo hasn't really proved anything against the Lakers this postseason. More important is having two of Amare/Lopez/Frye/Amundson on the floor at all times.

(this post brought to you with the use of http://www.popcornmachine.net/).

So to just throw out a wild example, suppose Phoenix' hypothetical D lineup has never played against the Lakers' hypothetical B lineup. Then there is no data involving this particular matchup in the results. The data is being simulated through estimations. How well do statistical simulations emulate real world examples? To my knowledge nobody has yet found the means to ensure a good fit a priori -- we say it's good if the results are close, and say we messed up if they are way off.

Maybe a better way to describe the adjusted plus/minus would be to say that it "adjusts for level of competition and level of teammates". How well does it do that? I'd be interested to see a comparison of the Laker bench lineups vs. the Sun bench lineups in the first two games of the playoffs and the regular season. According to my cursory inspection of the stat tables, the Suns bench should have killed the Laker bench, but the opposite happened in the first two games. Then, it seems to have flipped in the last two series as the Suns' bench killed the Laker bench. And it seems like the differences have been by wide margin, not just a little bit.

I think the best way to use these stats would be to compare lineups within a team, assuming the coaches are taking into account the matchups, to find out which groups are doing well and which ones were not, just in case the coaching staff was having delusions regarding certain lineups.

We're probably on the same page though regarding specific matchups. I'm just trying to warn against playing certain lineups just for the net rating regardless of the competition, and you're trying to steer me away from disregarding them completely. I do believe this data says something, I'm just not exactly sure what yet. :)