I think there is some truth to that, but there's also a reason that Garrett lines up on the defensive right side MORE than the other spots. He has better moves from that side. But it doesn't stop them from moving him around to keep offenses from being able to do what they do to TJ.
And yes, the defense around TJ is also holding him back. When you have 5 OL, and a RB/TE that is 6 guys you can use for protection. Then the Steelers line up with 2 OLB, and 2 DL... It's a numbers game that never works out in the Steelers favor. On rare occasions they have tried to put Herbig next to TJ, but the numbers are still 6 on 5. You need to force the OL to wonder where the pressure is coming from, create matchups in YOUR favor...but right now they are playing INTO every offenses perfect scenario. Play off the WR, chip or double TJ, get the ball out fast, it's just pitch and catch.
Since they have Ramsey playing safety now, they should be able to keep 3 DL on the field at all times. But they need to send a blitz from somewhere, use stunts, something other than just rushing everyone straight up the field while being outnumbered.