You are correct. So look at OPS instead. I don't care that Moncada is hitting .219; I do care that his OPS is .695. And looking at month-by-month, he did .877, .582, .592, .749, .606 so far. One excellent month, one average month, and three Engel months.
The fact of the matter is that Ks must come down. Right now, he's striking out at a 35% rate. If he could get that down to 27% (190 Ks in 700 PAs), he could be at least above average. A .325 BABIP (assuming 25 HRs, and this is roughly his BABIP in MLB time with us) and 10% BB-rate with that K-rate would give him 160 hits in 630 ABs (.254 BA). OBP of .329. Assume 30 2Bs and 5 3Bs, and he accumulates 275 TBs for an SLG of .437. OPS is .766. Not bad, and he'd certainly be a starting two-bagger, maybe even top-10 in MLB. But not Robinson Cano, as many (I think) were hoping for.
Now let's imagine if he can get down to current Kris Bryant levels (although I will add that Bryant started at where I have Moncada ending in the last scenario, but he was more polished, fine, OK). So give him a 20% K-rate, like Bryant attained last year. 140 Ks in 700 PAs. BABIP of .325 (and because he's not K'ing as much, we'll predict 30 HRs). Some of those looking Ks have now morphed into well-deserved walks, so he has a 15% BB-rate. That's 105 BBs (elite batting eye- this is totally possible). That BABIP and aforementioned assumptions gives us 168 hits in 595 ABs, for a .282 BA (OBP of .390). Assume 35 2Bs (again, less time striking out means more time to drill the ball into the gap) and 5 3Bs. That's 303 TBs for an SLG of .505 and an OPS of .899.
That is what we traded Chris freakin' Sale for. But the Ks must come down.
P.S. just for fun, if I took the 20% K-rate but kept everything else at his 2018 rates, here's what you'd get in 700 PAs:
ABs- 627
BBs- 73
Hs- 178
2Bs- 30
3Bs- 7
HRs- 22
BA- .284
OBP- .359
SLG- .459
OPS- .818
That level is reached simply by cutting his Ks (albeit significantly). That's all based on his exact rates for BBs, XBHs of each type, and his current BABIP. No improvement except the K-rate. If he can start being aggressive earlier in counts and defensive later in them, he can be a perennial All Star. And like some have said, teaching Yoan to be more like Tim Anderson will be a lot easier than teaching Tim Anderson to be like Yoan.