I agree with the general consensus that the fights so far are lame, pointless and counter-productive. But there are a lot of angles here and a lot of loose ends. Yes this tournament will end before it's completion but for some reason I think it will happen closer to the end. There is no team eliminations so from what I gather it's point base, strongest to weakest.
I don't think Zeref is directly involve but someone that is acting on his behalf.
Raven tail has been a thorn in my side since they were revealed, I mean they are a freaking dark guild.
Sabertooth is a bunch of hot heads but they seem to have the fire power to back it up, and there is the clash of the Dragonslayers to consider.
I don't think the arc is going to end anytime soon and it is just the beginning of something a lot bigger, something that will impact the story greatly in the future. But there are a lot of major gaps since the seven year time skip and I think some of that will be filled in before Zeref's plan is completed.