I'm a Kingery fan, too. Still, Cesar has opened some eyes. Is he a "what you see is what you get" player. I guess so; established players almost always are, eh?. But what do we "see" with Hernandez? We see a .372 OBP over the past two seasons - over 1,199 plate appearances. That ain't chicken feed, folks.
Hernandez did this with a .294 BA, and with 127 walks in those 1,199 PA - that's a BB% of 10.6%.
Kingery has produced similar OBP in the past two seasons, in Clearwater (.360 in 2016) and Reading (.379 in 2017). He has not equaled Cesar's major-league BB% (7.9% in 2016 in Clearwater, 9.8% in 2017 in Reading). In Lehigh Valley last summer, his OBP was .337, his BB% was 4.5%. He's shown potential, but he hasn't done it yet in AAA, much less the majors.
Now, Kingery brings more power to the plate than Hernandez. But frankly, I think we have to consider his Reading SLG (.608) as an outlier that's not likely to recur in any other environment. He slugged .449 in Lehigh Valley - and that's higher than anything he did prior to that. I don't know if the power surge last season (the AAA power) is real or not (he only had 286 PA) As of now, it's a single-season phenomenon, that occurred mostly in the hitter's paradise of Reading.
So I really think Scott Kingery needs at least a half-season, if not a full season in Lehigh Valley. He needs to be there long enough to experience a slump or two, long enough for AAA pitchers to develop a book on him, long enough that he has to adapt and adjust as the league's pitchers adjust to him, and find his weaknesses. That's the only way we'll find out if he's the real thing.
In the meantime, a .370 OBP out of our second baseman (in the top third of the batting order, with JP Crawford and Carlos Santana) isn't exactly a problem. That's post-season calibre table-setting. With that top third of the order, if the middle-order guys can generate solid SLG, this club will score runs.
Yes, we need better pitching. But you know what? Sign a free agent (forfeit the third-rounder if you have to); it's just money, which they have in abundance. If Kingery takes the next step, then yes, trade Cesar to a contender that needs a table-setter in August and September. But let's not assume Kingery will take that next step; let's wait and see.