Not in my opinion hes not. He still has games where nothing comes of for him. Not the case with Martial. Honestly, if we had a better coach people would realize just how good Martial is.
The same could be said of Martial. They're still developing.
That said, Rashford seems to have found himself in the left forward spot and made it his own. He's more consistent and looks like he's up for it almost every game. On current form he seems a step ahead of Martial.
Martial is very, very gifted, probably more so than Rashford, and his close control is a joy to watch, but I'd like to point out that most valuable player is not the same thing as best or most gifted player.
Not to derail the thread but with Rashford doing well in the left attacking spot, he's no longer competing with Martial, who prefers CF. The threat to Martial's spot in a year or two would probably be from Greenwood.