I imagine what Jackie is saying is that he sees Erskine best in a free/freer role than he had been playing a year ago. Similar to Harkins in that not much (if any) defensive duties will be required but different as Harkins played mainly down the flanks with his free role and Erskine is thought to be better or more effective thru the middle. I also believe that McNamara/Donnelly, as McCall before, predict considerable potential with the lad. The more last season progressed the more I think it looked that their prediction wasn't as ill founded as I thought earlier.
I suppose then that the other players especially midfielders will have to have quite rigid positioning to compensate. In that respect you could say that the side is built round Erskine. In practice tho', even if he's less inconsistent, I think he'll be subbed as often for tactical reasons than due to his form.
I get the impression that a player whose team is built around him is expected to play 90 mins every week. I can't see that happening with Erskine. If it was the case then I reluctantly have to agree with above post.