There is a motte-and-bailey maneuver going on here. You assert references to entirely unverifiable psychologisms like "morale," and then, when challenged, you retreat to characterizing player performance (perhaps hyperbolically — our rotation of all #5 pitchers is somehow 3rd in the AL in SP WAR). The quoted above was not the argument everyone was responding to, which was much more focused on vibes.
You don't know what Dalbec's season means to the other players in the clubhouse. Maybe they consider supporting a struggling teammate to be an important aspect of being a good team mate, rather than demoralizing. I don't know. And that's the point: I don't know. And I really can't know. I don't think the clichéd quotes that make it into the press really have much of a bearing on this. No one is going to tell Jen McCaffrey, "Bobby's been hitting terribly and Chaim didn't replace him, and that bums me out, so now I will also hit terribly."
With that I will drop it.
We can drop it here, though indulge me with a response.
I trust I might have some faulty logic in there. Though maybe not. To clarify: I'm simply saying that the players most notice the poor performance of their mates, and certainly notice when their competition out does them by acquiring talent to help with the final push. And that that combination of facts perceived and digested could hurt morale. Which in turn might have an impact - temporary as it may be - on performance level.
Sure, we may not know what Dalbec's season
means to the players in the clubhouse. Just like we don't
know what anything means to anyone in any circumstance, frankly. It seems
you've retreated to an epistemological argument that basically trumps discussion by asserting there is no basis for an impressionistic observation about anything that has any merit in any circumstance.
But our own experiential understanding of things can provide some insight. I offer again my own experience being in a public performance field (theater and TV). When you're in a play, and one cast member just can't hack it ... they can't keep pace, they're too quiet or selfish on stage, can't remember their lines ... as much as people might like that person, they'd prefer a quality pro at the top of their game comes in in their place ... and then, THEN, the person gets fired and people feel badly for a minute. And then their replacement comes in and it's a hot shit super talented actor who's had some big gigs recently, and they come in prepared and energized, and everyone is pysched as shit and the performance level of the entire ensemble gets better. This is not conjecture but something I've experienced in iterations over and over again over 30 years in the field.
And if management didn't fire that actor who couldn't hack it, that actor who was bringing the whole enterprise down, the other actors are pissed, let me tell you. Again - doesn't mean they don't feel for that person as a person.
So ... it might be common sense: the players want to win. They are pros. They want the best team possible. And when the guys who run the organization don't help provide the best team possible, it could feel like a gut punch, and that might have a temporary effect on performance levels.