The very fact that there is escalation is his attempts to mutilate, through to Kelly, demonstrates that he did not understand, but was learning, how to mutilate.
So from the get-go, the man learning to mutilate does not resemble the learned man who can amputate, dismember and eviscerate.
Torso man would have known what to expect in these bone obstructions from experience, yet even JtR finds himself trying to do the same thing again, on another victim without success.
What this does is explain all the wounds JtR inflicted. There is a combination of successful attempts to mutilate some part around which are unsuccessful attempts to mutilate some parts. This is going all the way back to Nichols.
JtR is like a kid probing and playing around trying to find what he wants.
Torsoman didn't have to play. Should Torsoman have been the mutilator, the mutilations would be site-directed, efficiently completed and not the jagged, semi-frenzied, smash and grab, that is even evident in Kelly in part.
Torsoman would have produced a completely different set of injuries in the C5 if he intended mutilation.
Bona fide canonical and then some.