It's not really all that complicated, writing that someone has been one of our better players implies good performances, i have no idea why you're pretending otherwise, especially when you combine it with your other posts pretending he's a nailed on starter. If Cavani keeps performing like he has, he'll be a nailed on starter, if Rashford keeps performing like he has, his position is up for grabs, there's a bit of a difference...
I doubt anyone will disagree that Rashford has been poor, just less poor than the rest of the alternatives.