I'm making the argument that you don't alter your decision making just to save Edwin Escobar. Nor do you worry about just DFAing O'Sullivan when the time comes.
I also like how Christian Vazquez and JBJ were considered mediocre minor league talents.
And all you did was just name a bunch of guys who would be lit up like a dumpster fire. They were not better options and losing Escobar isn't something you lose sleep over.
Vazquez was absolutely considered a mediocre minor league talent before he was added to the 40-man roster after 2012. He had just capped his regular season with a cool .205/.280/.260 SSS showing in Portland before hitting .257/.395/.429 in a surprise AFL showing. All-glove, no-bat catchers are littered throughout professional baseball. But the minor league evaluators took a chance to protect him from the Rule-5 draft, because of his defense.
JBJ was absolutely considered a mediocre minor league talent after his disastrous 2014 showing in MLB. I won't even bother quoting stats, they were so bad. He looked to all the world like his ceiling was lifelong AAAA guy when he couldn't even hit in Pawtucket at the end of that season. But the Sox kept him around instead of sending him to DDski's Tigers, because of his defense.
Pitchers don't have defense.
So while it's really easy to say one shouldn't worry about DFAing mediocre minor league talent such as O'Sullivan or Escobar, you run the risk of DFAing exactly the pitcher you need later. Like Breslow, for example: 47 IP of 1.91 ERA in 2008 would have helped that team a lot more than Timlin or Aardsma or Hansen...or Corey, who was kept instead, to give the team 6 IP of 10.50 ERA ball. And it sure would have been nice to have just one more reliable reliever in Game 2 vs Tampa, too.
But Breslow didn't throw hard even then. He was considered no great loss, just like Corey was a few weeks later. And it's true, a career of 6.7 WAR as a reliever doesn't make Breslow one of the greats, just one of the usefuls.
Still, a lack of useful arms is exactly what plagued DDski's bullpens with the Tigers; thus, it's an interesting question to me. And one I think worthy of some additional research.
The minors are a numbers game, aside from the top prospects. But no prospect is a top prospect as a relief pitcher. And mistakes will certainly be made by everyone. But even if Escobar never amounts to anything useful, taking him off the roster for Cuevas -- also the definition of "meh" -- for his 2 1/3 IP, is a head-scratcher.
As is calling up O'Sullivan.
Because, unless the Bannister connection really has made a material difference from what he was outside of San Diego to what he is now -- and it might well be -- there's no real difference between handing him the ball, or Owens, or Elias, or Cuevas, or Johnson. None of them look to be any more or less useful than any other, at this moment in time.
So smart money seems to me, to hold onto as many as possible and keep as many of them around to see what each might become, given more time.