Let's set aside the injuries for a bit and look at King's game performance.
1) King's early success his rookie season was, like Randall as a rookie, partially a function of teams not throwing much at him, an unknown quantity with insufficient NFL tape. Consider PFF's 2017 grades where King had 50+ snaps:
https://www.pff.com/news/pro-kevin-...ite-performance-of-his-young-promising-career
In the 2017 week 2 Atlanta game King was thrown at only 3 times with no completions. In the week 6 San Francisco game, that's the rookie C.J. Beathard underthrowing Goodwin on the highlight play in the above link, a QB who finished that season with a statitically meaningful 69.2 QB rating on 5 starts and 224 passes.
2) While the 5 games in the above link, averaged out, might indicate promise with some rookie lumps taken along the way, his other games were, in PFF's opinion, pretty dreadful given his final 2017 grade was a dismal 40ish. In King's second season, his grade improved to an underwhelming 59.7:
https://www.pff.com/news/pro-draft-...econd-round-pick-since-2015-nfc-north-edition
"Across 685 NFL coverage snaps, King has allowed a passer rating of 96.5 while failing to record a season grade greater than 60.0."
3) It's not like the eye test says anything different. There are two troubling aspects of King's game to date that have nothing to do with his shoulder injuries. First, he lacks quickness reacting to breaks, surrendering separation on short routes, the kind of thing a Brady, Brees or a Goff will pick on all day, while having to rely on recovery speed and length on deep routes. Second, he's often looked clueless in zone, better in year 2 but still not good. These two aspects of King's game are, by contrast, not Alexander vulnerabilities. Alexander has to fine tune for lack of length but otherwise is skills toolbox is superior.
4) One comment above referenced back to draft comparisons to Richard Sherman. Well, all kinds of prospects have been compared to Sherman. King being 6'3" makes him particularly vulnerable to that comparision. Even Josh Jackson drew the same comparison. I guess if you're 6'1" or above you are susceptible to that comparison. What differentiated Sherman in his prime was his ability to slow and disrupt routes, whether knocking receivers off their desired path and disrupting timing in press coverage or riding and slowing the receiver with bumps and hand checks down the field compensating for his lack of long speed. After that, it was length and ball skills taking over. While length and ball skills make for an apt King/Sherman comparision, it's the knack for route disruption just this side of drawing flags that made Sherman what he was, and that is not an apt King comparison.
5) To digress, the Jackson/Sherman comparison goes to the other side of the coin, a comparison based on Jackson's physical play against the route. Unfortunately, Jackson early on in 2018 was on the wrong side of the flag equation. As he adjusted his game to NFL officiating, his affectiveness went down. We'll just have to wait and see how his year 2 adjustments look.
6) Another comment above stated that King needs to play off coverage presumably because of his shoulder issues. That's not an answer. Given his vulnerabilities out of NFL caliber breaks and NFL caliber deliveries, the ideal answer is to develop press skills which would then make some kind of Sherman comparison, however pale, somewhat reasonable. In the final analysis, if we can't say at some point, "King is a good press-man corner" then I highly doubt we'll be able to say, "King is a good corner." As for zone coverage, King has the equivalent of a little over half a season of snaps,. From a game experience standpoint, he's like a rookie around week 10, with a scheme change in the middle. I'm willing to give a partial pass on his zone skills under those circumstances, but it's something to keep an eye on and the results so far have not been auspicious.
7) Another comment offered the observation that the injuries are not King's fault. I suppose if this is a case of inherently loose shoulders that's true in an it-is-what-it-is kinda way. That is, of course, irrelevant just as it is irrelevant if we say that a player has insufficient talent to make the jump to the pros. That's not that guy's fault either. But there is one think King can do to limit the chances of shoulder reinjury. Consider the following 2017 highlight tape:
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On of the things we like about King is his agressiveness in attacking the line of scrimage on runs and screens as evidenced in this tape. However, one aspect of that aggressiveness is his shoulder tackling when he's able to get a bead on the ball carrier. The tape shows he's a good ankle tackler when pursuit or the angle requires it. King needs to purge himself of the inclination to try to light a guy up when the opportunity arises. He needs to consistently target low as a necessary "business decision".
8) King's most admirable trait is his willingness to play through injury. By his count he popped the one shoulder some ten times during his rookie season, had it popped back in, then went back on the field. Put him on the warrior list with Bulaga. There's a good chance one of those shoulder hits in the above tape put him in the sideline tent for one of those interventions, then back on the field.
In summary, King is not "the man". Performance and injuries tell a different story. Concluding that he is relies on the most glowing of draft scouting reports while ignoring what has happened over the past two seasons. Might he become "the man"? I suppose it is possible but returns so far suggest otherwise. If there is "the man" in this corner group, Alexander is the clear leading candidate.