There are such things as "bad trades", which if it is ultimately comes down to perspective on a subject.
The only justification that I can believe on the end of Dallas is that they want HarryHook back in to shotcall, but that doesn't make much sense, since Custa does that was shown to have the most positive impact on the in-game atmosphere overall, but there's not really anything to compare that too since we (the public) don't have access to their scrim/full match comms. Unless Dallas and their management are really doubling down and having the team build itself up with a stable roster that's going to start most games and so that they can focus on more important things, like the team they're facing and what they're likely going to run and prepare. These things are what OWL teams need to be focused on doing, not figuring out who is going to be in the next batch of contestants on musical chairs with the Fuel.
As far as the Valiant, the reports that uNKOE isn't helping the team atmosphere is a good justification, as team atmosphere is equally as important in a team as the players itself, but knowing that Custa isn't going to be filling the Zen role that was previously occupied by uNKOE confuses me. Is KariV going to remain on support ? What about Verbo? Is there still going to be a language barrier between the Koreans in the team and the non-Korean speaking players? I personally don't keep up with LAV that much but to my knowledge these questions haven't been answered that clearly, and I guess from my perception of the matter, the LAV staff don't entirely know that answer yet either. Custa will certainly bring a positive environment if he's shotcalling, but will likely come at the expense of Verbo's playtime.
I know it's nerd writings and there are almost always always more questions than answers but sometimes there is more than meets the eye with trades like these. There are more moving parts than just "one player in and another player out".