If a coach has their team play a slow tempo against a very good rated defense (PR) would that not allow the defense a longer time during the poss. to creat a turnover or a challenged shot, thus a lower FG %? I hear many coaches saying play a slow tempo to limit the number of poss. the better team has, i get that, but doesnt it allow for the better team defense more time to take over and win the game? On top of then you are getting less shots up. Any thoughts?

If this were real basketball, yes. It is hoops dynasty though. Does anyone know if they actually make you throw more passes when you play slowdown? They could just as easily just add 5 or 8 seconds to the average offensive pocession for your team.

ok, i agree with that, so why is it better to use slow tempo for than?

Against a superior team, it's better to slow it down to limit the number of possessions and increase variance. Totally independent of whether it decreases turnovers. 

Does it decrease turnover rate? I have no idea.

I believe it also helps smallify huge advantages that your opponents have.  If they're going to out-rebound you by 15 at normal tempo, and they only do it by 8 at slow tempo, you're reducing that advantage.

Add: I don't believe it's a zero-sum situation, where the advantage stays relatively the same at the lower end.  I'm sure there are smarter people than I who disagree.

I think you do give up some offensive efficiency when you go slowdown.  The idea is that in a game with a big enough disparity the increase in variance may be worth it.  If you just watch basketball regularly you know that even in real life the lesser team has a much better chance of leading or even being close at halftime than at the end of the game.  If you have a true shooting % expectation of .420 against a team, over 10000 shots you're pretty much shooting .420.  Over 1 shot you're shooting either 0 or 1.0.  The idea of slowing down is that you have about as good a chance as shooting 50% relative to a 40% expectation value over 45 shots in the slowdown as you do of shooting 50% relative to a 42% expectation value shooting 65 shots at a normal tempo.  And you have a better chance in the slower game of the opposing team shooting 43% relative to their 50% expectation value.  If you get lucky and shoot 50% and they shoot 43% maybe you can win the game, even if they still outrebound you and generate more turnovers.  Although the same logic applies to both rebounding and turnovers - shorter game, more chance of an outlier result that  allows you to compete.

This is more true now than ever since they instituted the logic that pushes everything towards the mean if you're too deep onto one one of the skinny ends of the bell curve.  You really need to end the game before the regression to the mean logic really slams the door in your face even if you are getting a little lucky.

I should additionally point out that I think some coaches over-utilize both the slowdown and uptempo offenses by a huge margin.  If you can come up with a gameplan with which you think you might be able to be competitive with the other team then slowing down and hurting your own offensive efficiency is clearly not to your benefit.  The time to go with the slowdown is when you really can't see any way in which you should be able to compete with the other team.  They really outclass in you in most or all phases of the game.  In this situation you are basically recognizing that the only way you're going to win the game is with an outlier result.  I would say you should consider yourself under 30% to win the game at best, probably under 20% would be a better standard.  At that point it might make sense to take the strategy that technically hurts your team but increases the odds of an outlier result since you're relying on an outlier to win anyway.

It also doesn't hurt if you think your starters can hang with theirs but you have a big dropoff behind them...

I'm not sure I agree about slow down hurting offensive efficiency to the degree that you suggest.  I don't have the ability to evaluate it statistically, but it seems to me that some of my teams have thrived in slow down after struggling in normal tempo.  I can only guess it's the advantage of the the starters vs. bench factor (starters playing longer).  One could agrue also that in real life a slow down team -- perhaps a better word would patient and deliberate -- can really frustrate opposition and exploit a defensive break down (playing defense hard for 35 seconds for example requires good discipline).  This assumes the team isn't just standing around but actually running an offense...

That said, I realize the engine may not work that way and penalize slow down.  It would be interesting to know if there are some offenses that have a improved efficiency with the slow down, just like you would imagine the fastbreak offense would have improved efficiency with uptempo.

I think the efficiency of slowdown depends on what your opponent does. If your opponent runs uptempo against your slowdown I think you get more possessions with that slowdown efficiency, same with a normal tempo to a degree, but if both teams play slowdown I think the variance is that much greater.

I don't think that running slowdown negatively impacts your offensive efficiency.

+1

Another thing that hasn't been mentioned here is fouls. The faster the tempo more possessions more fouls. This creates a couple of effects.

(1) Teams with weaker benches are hurt because not only because their best players are more tired but also because they are more likely to get into foul trouble 
(2)Good free throw shooting teams benefit even if both teams have more free throws
(3) Teams that tend to go to the line alot benefit because of the discontinuity caused by the bonus. The first 7 fouls don't necessarily result in free throws where fouls after 7 do. This means teams who get fouled alot get into the bonus faster and have a greater percentage of their plays resulting in free throws (which tend to be the most efficient way to score).

Last season I played uptempo exclusively. This was because I had a deep bench, fast/athletic team, whose top three player at getting to the line were rated A, A- and B+ in FT. I also felt that I was better than, or at least equal to most of the teams I was playing, so I didn't have much to think about around wanting to slow the game down for reversion to the mean purposes.

That's the thing to warn people about - you need to be able to draw the fouls in the first place.  You don't go to the line a lot just by playing uptempo.  That shiz is risky.

Definitely, you need to feel that you have a significant advantage in drawing and making free throws to use this. I was just pointing it out as an effect that hadn't been mentioned. The reverse is also true. If you think your opponent has an advantage drawing or making free throws, this could easily backfire. With every setting in the game, it is about trying to maximize your teams strengths and minimize their weaknesses.