So I've done about a dozen battles now, and find that the opponent matching doesn't seem to do a good job. Prior to the update, arena battles weren't difficult, and I'd win 80-90%. Like many here I didn't fight a lot, but would just for variety. I think I have a record of 3 and 9, mostly fighting opponents 10-16 levels higher, and with 6-10k more hit points. I haven't really looked at how even the 3 battle scores are, but given the margin of defeat, they aren't close. The win-loss ratio makes arena battles unappealing at the moment.