Norman should be “at least 8-C” if you ask me. I get the idea of Tom holding back but, in context, that makes no sense to me. If May was in obvious danger at the time, and if Tom saw Norman tanking his punches, why would he still feel the need to hold back?
Also, three things to note:
Norman broke Tom’s ribs during their first fight.
For their final fight Tom was wailing on him with a bunch of punches, he never drew blood from Norman’s face or even left a bruise.
In SM1 Norman was regularly above Tobey.
Obviously Tom can still harm him, but Norman is clearly much stronger and more durable.