Regression is similar to correlation, just more powerful. For example, you can control for covariates (stuff that could have an undue influence on results; e.g., sex, gender, other hidden variables could explain results... so you want to account for that, making sure you "control" as much as you can to draw the conclusions you want.
Second, regression allows you to directly test the influence of moderators (third variables)...same as covariates, really, but instead of saying I want to test the relation between A and B (while controlling for undue influence of C), the C is a variable of considerable interest (e.g., does C significantly influence the result of A and B?)
I chose minutes and points because they are the 2 variables that seem most inconsistent for KO. The basic question was "How much variance in his scoring can be explain by variance in his minutes?" Basically, if MPG predicted 100% of his point production, then KO's ups and downs with re: to scoring could be entirely explained by ups and downs in minutes.
Results indicated a moderate relationship... just 50% of variance in scoring is attributed to minutes. That's a lot, sure... but only half. So then the question is "What else is accounting for his ups and downs in scoring?" Hence the moderation analyses... which are intended to determine variables that significantly influence his ups and downs in scoring, importantly, over and above playing time (you're controlling for playing time, here... we wanna see if anything contributes beyond it in order to shed further light on the story).
So TOs, fouls, 3P % didn't do it... but 2P % did. It accounted for 5% more of his ups and downs in point production, beyond just minutes played. So that's interesting because it suggests his offensive production (limited to just points here, unfortunately) is related to ups and downs in shooting, even after taking into account the variability in his playing time. While it's not really possible to account for all the variability in his scoring (or any component of his game, really), there still remains 45% of the variance in his scoring left unaccounted for.
Just above Hwang is making some suggestions that may help further explain the relation between mins and point production for KO. That's really good stuff. Any behavioral observations (stuff you see on the court) you guys may have could potentially be testable (albeit difficult, but I don't care about that)... and shed some more light on his offensive ups and downs (again, beyond just PT).
I hope that is at least somewhat helpful. Again, feel free to ask any questions.