I guess it depends on what "ace" we're talking about and who the Sox would have to give to get them.
On one hand, Hamels probably wouldn't saved this team on his own, but the Sox would have him in the rotation going forward.
if the Sox were to give up one or two players that are now on the ML roster to get a TOR pitcher, there's every chance that the Sox would be in even worse shape.
Betts and Bogaerts are two of the few bright spots of this dismal season.
Frankly, I don't think Hamels or Shields are elite enough to have taken any pressure of the the rest of the staff.
Scherzer, maybe...