I dont see anything wrong here, based on only these things that is.
DPS is doing "low" dps, and I use term low very carefully, because they are only doing base damage + small amounts from gear. Its "always" been like that.. Low base damage but good scaling.
Then comes tanks who are mostly good base damage but bad scaling..ofc good base damage classes triumph at very start. Vengeance is extra too.
Once dps gets proper gear(not blues) it balances out, like always.
In some cases of course its, and I hate to use the term, "L2P issue".