"Jameson won the title outscoring Jeffries on a unanimous decision."

To me, the above line reads. However, I notice most people write it:

"Jameson won the title by outscoring Jeffries on a unanimous decision."



Can anyone explain why the 'by' is needed please?

The first example uses a present active participle (in essence an adjective describing Jameson). Many would like to see a comma before 'outscoring', but there is leniency on this.

The second uses a gerund (a type of noun formed from a verb). It is linked to Jameson with the preposition 'by'.

In sum, both are correct.

Thanks.

I must have a blind spot to this because, no matter how long and hard I look at it, a line such as: "Jameson won the title outscoring Jeffries on a unanimous decision", reads to me. I wish I could understand why it doesn't.

I think it is fine. I have most trouble with "on a unanimous decision." I would have preferred "with a unanimous decision."