That's not even a Death Match yet (which would be the fully max Thanos/Kang opponents no matter what you were using), but is just normal progressive increasing of difficulty. Say at about Streak=3 you will get matched against an entirely same ranked team as your own. Then every match above that the difference between yours and opponents increased by 1 rank for just one of the 3 individual fights.So 3 matches later all 3 opponents would be 1 rank higher then yours. And 6 matches later (which would be about Streak=9) you will be facing opponents 2 ranks higher than all of yours.Now, you ordered yours different from Opponent, which is why you have first at 1 rank diff, one at 2 ranks diff, and last at 3 rank diff. But average is same.At around streak=10 you could face the Thanos/Kang teams, and depending on whether you were doing 4^ Feature or 5* Feature Arena would dictate whether your team above at that next Streak # could handle a max 5* (probably winnable there) or max 6* (probably not winnable with your lineup in that pic). But at least Thanos/Kang opponents don’t have any Mastery so their ratings are lower than a real opponent at those ranks.