Aldridge is averaging 25/10 or so since Roy went down. Griffin is at 22/12. I don't think Griffin has a lot of upside in the rebounding area (historically there isn't much room to expand beyond 12/game), so his upside will mostly be realized in scoring improvement and defense.
When people say Griffin will be much better than Aldridge offensively, what does that mean? That his team will be able to throw it into him in the post and he'll score against anyone like Shaq did, thereby garnering 27-30 ppg, year after year for a decade? It doesn't seem likely. He doesn't have those kind of skills.
So what you are really talking about is a Nowitzki/Amare/Barkley level of offense. A perennial 25 ppg guy who maybe jumps up to 28 ppg for a few prime years. Which is pretty much the same career path that Aldridge seems to be on.
Griffin got on that path 4 years earlier than Aldridge, so maybe he racks up more points over his entire NBA career. But he's also ridiculously reliant on his athleticism and he's already undergone major knee surgery once, so even that isn't a sure thing.
Then you have to bring in how both guys are used in the offense. Griffin seems to be in the Nowitzki/Amare mold of big men where you design the offense around timing ball movement so that he's in position to get a great shot.
Aldridge seems to be more in the mold of big men like Shaq and Duncan where you throw the ball into the post and then watch the other team scramble around trying to deal with it.
The first type of big man augments a well-functioning offense. The other creates a well-functioning offense. I'll take the latter any time, all else being roughly equal.
