public async Task <List <Match> > GetMatchesAsync(string playerId, int size) { List <Match> matches; try { matches = await apiService.FetchMatchesAsync(playerId, size); } catch { throw; } for (int i = 0; i < matches.Count - 1; ++i) { if (matches[i].ELO != 0) { Match nextMatchWithElo = matches.FirstOrDefault(m => m.Index > i && m.ELO != 0); matches[i].ChangeELO = nextMatchWithElo != null ? matches[i].ELO - nextMatchWithElo.ELO : 0; } } return(matches); }