Simple solution: Turn off battle chat. I usually just use group chat when in arena in case a group mate needs me for something.

I'm a "whale", I don't even see what you write to me in arena, ever. You can either fight me, or you can leave. I don't like arena as it is. My goal is to finish the requirements and leave. You begging me to win just means you or others have more of a chance of hitting me again later if I give you the win every time I see you. I'm not going to just sit there and let everyone that has no chance get free wins all day. I don't know you, I'm not obligated to give you a win just because you beg for it. In Matsuri, sure I'll give away wins because you only need 5 wins and it's a timed event. It's harder to win when you are lower levels/power. In arena, most power is normalized and you have a month to do arena, if there are too many "whales", then give arena a break and check back later.