What doesn't make Marshall a playmaker? He can go up and grab the ball with some of the best, he is one of the best at YAC, and has great hands. The only thing you could've put against him was home run speed which he has worked greatly on this year and is looking to be faster this year.
Playmakers are a threat to score from anywhere on the field, playmakers are guys that turn short gains into long gains and make moving down the field much quicker and easier. Marshall is a a guy who is going to move the chains(which is important) but he's not a playmaker.
Get out of here, didn't you see him in denver? He went up and got the ball and he could make great YAC. Have you ever seen his Cowboys game catch? He did that on a dailiy basis. He's more of a playmaker than Santonio Holmes is in every way.
How does one have such great YAC yet only average 12 yds per rec?