1) What consistency did Jones demonstrate? Surely not after he returned from injury.
2) "Overrun" with Mitch Keller - I love you man, but even if the Pirates were a playoff team, Vegas would have them as underdogs in a Keller-started game.
Sorry, I don't mean overrun in the sense of 3 pitchers who will totally dominate a la what the outrageous expectations (though obviously warranted) for Skenes will be headed into the year.
I mean that winning series will mean converting the opportunities of those pitchers and what we're able to get out of Ortiz, Chandler, Oviedo, Veteran Reclamation more often than not, but especially those pitchers.
Regarding Jones, if you just don't like him, I don't know what to say. There are reasons to be cautious and skeptical towards him, and he had some struggles in his half a dozen starts to end the year. But he bumped his innings up by about 50 and still had several very good starts by most any standard.
I will grant that consistency isn't the best adjective to throw around with him, and I also get that people don't love him on a game-to-game, I'm-watching-this-guy-and-sweating-the-Pirates-winning-or-losing-right-now type of vibe, but he has massive swing and miss stuff and even without accounting for a young player continuing to take steps forward, that translates to impact in the W-L column, especially if you can surround him with different kind of pitchers in the rotation which better allow the manager to use leverage arms as needed on days where the efficiency isn't as great as you'd want.
All in all, I really don't get the appeal of Casas for a pitching talent with as much upside as Jones. It's a mark on the Pirates and has been for years but for me it's kind of two separate problems that we can't produce any offense, even the most offense-only position of 1B, on the one hand, and using pitching depth to improve on the other. The perennial challenge of the latter route is that teams know the Pirates have few avenues to improve (since they refuse to even sign mid-level FAs) and in general, all teams are stingy with high quality young talent. Taking a swing at a high ceiling young talent like a Roman Anthony would be the perfect move, but teams don't usually want to give up that kind of player for anything.
I think we should be just about as protective as Jones, because he has the high pedigree and has already established himself in MLB. This is probably an unfair way to try and put it, because so many others also recently graduated with him, but an exercise that could help illustrate this is placing Jones on the FanGraphs top prospect list now. He graduated in the 55 tier, already a pretty high echelon for how stingy they are in terms of anything 60 or higher, and he would clearly currently be the clear #1 on the list (it's not fair to say because obviously if we re-ranked others, Merrill and Chourio would be above him easily). But I don't think any of that tier of prospect - i.e. guys like Basallo, Lawlar, Anthony, Jenkins etc - would be someone to trade for Casas, a pretty good, 1B only guy who might be able to reach 28-32 HRs if he puts a fully healthy year together.