Board Game Arena

i just played a game with very nice guys but at the end i saw something very strange , look the + 50 elo for the winner

First: He was the lowest-ranked player in the game; he was expected to lose, but he won, so his ELO boost is higher.
Second: He seems to still be within his first ten games of Catan on BGA, so his ELO boost will be larger to try to get him closer to his proper ELO quickly.