Gladiator was at full confidence in all of these occasions and it didn't stop him from losing to some of these people or failing to hurt them with his hits. Literally the only times the "muh confidence" thing was brought up was in his first FF appearance and in a fight against Cannonball. The "power varies" excuse doesn't fly here. And Ben has beaten people better than Gladiator before.
Based on what? Since you said so?
Based on the fact that he was as confident as when he performed his better feats and nothing implied that his confidence was wavering. So basically, based on common sense.