That’s just how it works. The math is simple. We traded Yonder Alonso, Yasmani Grandal, Edinson Volquez, and another dude for Mat Latos. Tonight, we lost. I mean, Mat Latos threw seven shutout innings, whereas Volquez, Grandal, Alonso and that other guy (which I refer to, collectively as Volonsandalberger) collectively threw seven 1-run innings. But Volonsandalberger did get some hits (and scored the winning run), which is more than Mat Latos.
The key bit is that we lost the game. Latos’ strong pitching? Irrelevant. The fact that the Reds couldn’t score more a single run off a starter with a 5.38 BB/9? Second verse, same as the first.
There’s really no other way to judge a trade. I mean, you could consider the relative needs of both teams, based on both position and timing, or even the need of certain players for a change of scenery. You could look at the comparative merit of all players at the time of the trade, and then evaluate the actual value produced over a long period of time, keeping in mind that the franchises may have had different purposes behind the trade, that bad luck is different from bad scouting, but that good player evaluation will help on the average of all transactions.
But that would be hard. Instead, let’s just look at how the first matchup goes post-trade, and call that analysis. We lost the game = worst trade ever.