Garland is supposed to perform better than he is.
Not as much is expected with Grilli because not much was put into acquiring him. (Rule 5)
Garland has been on the Sox for what... 5 plus years? He hasn't improved into a top starter like he should. He WAS a #1 pick after all.
Grilli is new. But, if he continues to struggle, he won't even be given the same leeway as Garland currently gets.
He will be sent outright to AAA or released.