Can't agree. We won 25 in a row. The toughest one was last battle in 8-streak where the only opponents my accounts could hit were two level 6 minis, but overall the total attack strength of the other syndicate fell into our range, plus or minus 10%. Luckily my syn partner was able to get very good IP from one of them in particular, so we won by a narrow margin.
Of the three battles we lost out of 46 fights, two were against 3-man streak teams with a DL stronger than my partner's attack, but really still within the range I'd consider normal.
It's possible there is something in the algorithm to make last of a streak tougher, but other than that #8 battle we didn't experience it. Quite the opposite in fact - our losses were on 1/4, then a win followed by second loss on 2/4, then on 3/6. Starting 1/6 again was trouble-free until 8/8