ROY is a stats award. It almost always goes to the player with the gaudiest stats. Unlike MVP, playing on a winning team doesn't really factor into ROY voting. In fact, playing on a bad team usually helps, as it means more PT and a greater role (more shots) for the rookies on that team.
Yes, it's only 3 or 4 games into the season, and yes, it was only against Golden State, but Gasol's EFF = 38 game was HUGE statically. Not only did he put up 27/16, he also had 3 BLKs and shot 9-11 from both the field and the line. At the end of the season, when the ROY voting happens, the voters won't remember that Gasol's huge game was against a weak Golden State front line, they will simply look as his statistical averages and vote accordingly.
Right now, Gasol leads all rookies with an EFF = 19.0, followed by Jason Thompson at EFF = 18.0. Rudy is currently 6th among rookies at EFF = 14.0. For comparison, Brandon Roy ran away with ROY in 2006-07 with an EFF = 16.51.
No single stat accurately predicts ROY. EFF comes close, but is trumped by a gaudy scoring average. Last year, Al Horford lead all rookies with EFF = 16.51, but Kevin Durant won ROY with an EFF = 15.61. The difference was Durant scored over twice as much as Horford (20.3 PPG vs. 10.1 PPG). Horford wasn't even in the top five in PPG among last year's rookies, but still came in second in ROY voting due to his strong production in other areas.
So, it's still way early, but right now Marc Gasol is definitely in the running for ROY. As he won't likely lead all rookies in scoring. So, he will need to at least average double figures in scoring, put up good stats in other areas, and hope nobody else averages > 5 PPG more than he does to have a chane at winning ROY. But, if he continues to put up solid numbers night in and night out (currently 13.0 PPG, 10.2 RPG and 1.75 BPG with 0.541 FG%), there's no reason to think he won't be a legitimate ROY candidate.
BNM