This is simple, Crosby wasn't as bad as the fans seem to think. Yes Crosby had a slight slump but his numbers were down more because of MM and where the offense was stalling out at.
Crosby was asked to kick nine 50+ yarders, which was more than 25% of his kicks all year and last year he struggled outside the 50, which is what killed his numbers and got fans so down on him. But inside the 50 Crosby was pretty much his normal self, probably should of made one more inside of 50 to be on average inside the 50.
Ross on the other hand, has all the physical potential to be a great player, didn't seem to be able to take that and make big plays on offense. Every so often he'd make a play you expect all the WRs to make and then he would follow it with a mistake of equal size.
On ST is why Ross was kept, for his returning skills, and when kept fumbling the ball and the coaches felt like he could no longer be trusted they released him.
I didn't want to cut either (I don't like cutting potential) but I don't see these two as the same in their different hot seats. Crosby was doing his job, but mainly just struggling with the hardest part of it (the 50+ yards), where Ross was struggling every where.