Issue Number 1: Just because Houston was left with the lesser of the two alternatives to choose from and decided to make that their choice doesn't mean that the decision was a close decision to make. They experienced Artest and didn't want him back. That does not mean that they upgraded the position in deciding to sign Ariza. On the contrary, given what each player had done in their career, what each player did last year and what each player would be expected to produce further, Houston got the worse player.
Issue Number 2: Regarding BBIQ, it is not something that can be measured with statistics or causes stats to go up dramatically. What a higher BBIQ will do cause a player to know who best to throw an outlet pass to to start a break. It will make a player know when to take the open shot and when to seek the extra pass. It will cause a player to time a switch properly to take a charge. It will make a player play defense on a one on two break properly and how to find the right slot to run on the break. It will tell a player when to make that chest pass and when to make that bounce pass. It will cause a player to learn to use the rim as an aide from getting your shot blocked and when to pass out of a double team. BBIQ, much like ability to play one on one defense is not a measurable item and if you have two players that have near identical stats, always give the nod to the one with the higher BBIQ, that is the player you want on your team because they make everyone else better players.
I think in your above post and other people who talk a lot about Bball IQ in general vastly overrate how important it is and want it both ways: BBall IQ is really important but doesn't show up in stats, and is possessed by whomever I say it is. The argument is that BBall IQ makes the team better on offense and defense, but such improvement doesn't show up in team stats of offensive or defensive efficiency. I instead argue that BBall IQ is, like length, strength, leaping ability, and court vision, a way to try to explain how a given player creates the results on the court that he does. Your team doesn't get 2 extra points per game because someone says "hey, Player X scored 8 points today but he has a high bball IQ worth 2 extra points," your team gets those 8 points because Player X, with his natural abilities would have scored 6 but, with his Bball IQ figured out how to get his 8. Perhaps BBall IQ would not drastically affect points, FG%, and rebounds...though it really seems like it would, especially FG%, which is a major Davis flaw. Wouldn't a smart player take more shots he can make? Your other examples would absolutely show up in team stats though. Making the correct pass should either avoid a turnover (measurable) or lead to more efficient team offense (measurable). Learning to use the rim is a means to a MEASURED end (FG% and/or %shots blocked). So is passing out of a double team (FG% and avoiding TO's and improved team offense). So are charges (Team defense numbers). However, by essentially all of the above measures, Maxiell has been the better pro. You are picking examples of HOW results are achieved, and actively placing more value on hand-picked ways of arriving at results instead of just looking at which results are better.
For example, let's say there are 2 different players who are exactly identical. Only one difference: player A can jump higher and player B is more creative minded. However, everyone agrees they are exactly identical defenders and rebounders. The main area of contention is offense. Player A has no moves. But he's a powerful leaper with a so-so jump shot. So he takes 8 shots per game and shoots .560%. He draws 2 fouls per game, shoots .600%. Player B is a poor leaper. So he uses beautiful fadeaways, up and unders, up fakes, etc. He also draws 2 fouls per game but, being more skilled, shoots .700%; however, he shoots .460% from the field, though everyone agrees he has a more creative, skilled, and intelligent shot repetoire than player A.
However, at the end of the day, player A scores 11.36 points on his 8 shots plus 4 free throws. Player B 10.16 points on his 8 shots plus 4 free throws, but does so in a much more visually pleasing way. At the end of the day, I'll take player A.
Let me be clear: The stats we have are not perfect. However, especially over time, they offer some generalities. Especially the team stats. If a player's Bball IQ is very bad or very good, it shows up, either in decreased team offense (because said player always botches fast breaks or won't pass out of double teams or makes bad passes) or decreased team defense (because they don't draw charges and blow assignments). However, nothing I see conclusively swings the argument either toward Maxiell or Davis, and I have not seen much from watching Davis that makes me think his mystical BBall IQ is much better for the team than any other average player's Bball IQ/better athleticism.