Why is it people just look at basic stats and not beyond that? DeRozan averaged 15 more mpg last season, which was a massive reason he doubled his scoring. He also took more shots per minute due to a larger role on offense. You stick anyone out there for 15 more mpg and give him more shots and he's going to increase his ppg.
Again, I'm not bashing the guy, and I believe he's got the makings of a good scorer, and have said so on numerous occasions. But 18 ppg on a bad team doesn't mean nearly as much as you make it seem. Lots of players can score if given the minutes and shots. What questions need to be asked are: How efficient is the scoring, do they score in the flow of the offense or have to force the issue, how effective are they when the game is close, and do they play with blinders on or do they make the right pass when they need to? Most importantly, can do help the team apart from scoring?
Unfortunately it makes a HUGE difference. As I stated above, a lot of players in the NBA, if given the shots, can score 20 ppg. Most NBA players have pretty damn good skills. My perfect player to bring up in this argument is
Tony Campbell. Campbell was a deep bench player for Detroit and the Lakers in the 80's, but when he signed with Minnesota, an expansion team, he scored 23 ppg. In fact, in his 3 years in Minnesota, one of the worst teams in the league, he averaged 20.6 ppg. Then he was traded to New York, a contender, he never hit double digits in scoring again, and never again played 20 mpg.
The reason is that Campbell could score, when the offense revolved around him and he was given enough shots. But he wasn't a good enough scorer to warrant taking 19 shots per game on a good team, and he wasn't very good at much else, so if he wasn't scoring, he wasn't of that much use.
A current player example is Marcus Thornton. The last 3 months of his rookie season he averaged nearly 20 ppg. Of course the team went 10-24 in that period. The next season, with a healthy Chris Paul, the team became a playoff team, but he couldn't get consistent minutes and was traded to Sacramento, a bad team, where he averaged 21.3 ppg. The problem in New Orleans is that he can't play defense to save his life, and does absolutely nothing else other than score, and he's not really a good enough scorer to warrant taking 18 shots per game on a good team.
Other players in this category: Corey Maggette, Al Harrington, Bargnani, Monta Ellis. All these players are very good scorers, but aren't good enough PLAYERS to do it on a good team.