People are rightly worried or pointing at the very high K% or BABIP and raises skeptical concerns about Cruz, but I think it's actually easier to underrate him right now. The counting stats are extremely impressive and I don't really think it's excessive homerism to say that what we're seeing from Cruz might be his floor: a 3 WAR player at the most valuable defensive position who adds 30 HRs and is a huge threat to opposing pitchers.
There's really no point in adding much to the chorus of obviousness that a 40% K rate will eventually bring problems, but what I think can also be overlooked and is also not really excessive homerism to point out is the extent to which teams are pitching around Cruz. Teams approach him in the same way that they approach Harper or Judge (Harper is probably the better comparison since he's a lefty).
I don't really think it's the case that he's up there lost or without a plan most of the time. I don't have precisely manicured numbers to back anything up, but it seems to me that after several weeks where there was less consistency between ABs, he's mostly stuck to a good approach and still not exactly gotten the results you want in terms of Ks.
Maybe the point where I stretch this too far is that there can be differences in Ks that can't be seen from looking at the box scores. Generally, Cruz sees 4-5+ pitches in each AB and is continuing to adjust to picking his spot to attack, instead of chasing an getting into bad counts quickly and going down with a strikeout after 3-4 pitches. If that were happening more often, then I think there would be more of a cause to worry if there's still a worse floor here.
But I think if you look at the overall approach, and then look at the minors and account for how much better MLB pitching is, it's more likely that there's another gear or two in there, and probably not even too insane to think that signs might point to a still-bad 30% K rate being all he really needs to tick the batting average up a little bit more, add another 5-10 HRs, and be more of a 4+ WAR player.
The biggest sign I think we could see that points the arrow way up is if he starts to draw walks at a decent rate. I think some of that with his recent stats can be fudged a little -- I'm thinking of the really awful calls he had against him in that game last week that turned BBs into Ks -- but this aspect of his game was also there in the minors and hasn't yet translated much. It's also obviously what guys like Harper or even Schwarber are able to do that make them better than just quite good 3 WAR players, which at the end of the day is still a pretty damn impressive rookie season.