I don't know. I have a hard time giving any individual player much grief when we are clearly terrible at coaching special teams all around.
I do agree that Stewart tends to play things ultra conservative. If he's not 125% certain he can catch the ball he runs away from it - resulting in those balls that land at the 30 and roll to the 10. But I don't get the fair catch inside the 10. I think everyone who has watched football more than 1 season knows the rule "Heels on the 10 yard line. If it goes over your head let it go." He shouldn't need directions from the sideline right before the play to know that.
We don't block very well on punt returns or kickoff returns, so that makes the returners jobs way harder.
But good grief, give me a kid who will catch the kickoff or punt and then run full speed up field. Way too much dancing, that doesn't work on kickoffs. Ever. Same thing on the few punts Stewart does try to return. Make one move and then head N/S.