When I said "when considering a trade, nobody cares about the impact of the players on each team", i meant all people evaluating the trade outside of the people involved in the trade.
of course, the people involved in the trade care about the impact the traded players have on their team.
why would the people not involved in the trade care about the impact of the traded players on teams of the trading parties? the people involved in the trade only care about if the trade is of equal value.
and, in this case, the trade is not of equal value.