I think it's a war for the first 4 rounds and then Arreola shows superior stamina and catches Seth sometime in the middle rounds, finishing him off. Highly entertaining bout that should be made though, decent eliminator for a Klitschko brother too.
I gotta roll with Arreola based on what we've seen thus far. . . Arreola has A LOT better boxing technique, and even hand speed than some credit him for, and he's just as tough as Vitali. . . Although Mitchell has displayed surprisingly crisp, and accurate combinations, he still gets a little lazy, and sloppy with his straight right (his left hook looked just about perfect, though - turned that bad boy over REAL NICE!). . . I think Arreola's punches would find home first, though. . .
Arreola takes the far better punch. It would be a war for a round or two, but then Mitchell's chin is getting shattered.
I disagree with those who say that Arreola would starch Mitchell in 2-3 rounds but I do agree that he'd likely outwork Seth to a lopsided UD if they fought right now. Seth needs a little more seasoning against guys like Boswell or Estrada before taking on the top 10ers.
Arreola, because of his very solid chin. Mitchell needs a new trainer... Kevin Rooney would be perfect.