If your name goes on the win, it goes on the loss too. Same font size.

Ownership cannot be selective. Stepping forward for the wins and back for the losses is visible immediately to everyone involved, and it costs more credibility than the loss itself ever would. Accepting both is unpleasant in the moment and it is what makes your word worth anything afterwards. The size of the claim should match in either direction.

After the next poor result, say your part plainly and without a list of circumstances attached. Do it before anybody asks. Then notice that people stop preparing their defenses around you.