Usually you can dig into advanced statistics and find your answer. Obviously, there will always be some outliers that SDS seems slow on that they likely are waiting on a larger sample size for, however, I do agree that Bryant got snubbed in this past update. That's not to say that I think he deserved an outright upgrade all the way to diamond status just for the sake of how he is playing so far through this season but he deserved more of a boost than he got.
So with that said, lets break down the numbers in comparison to his current attributes...
Bryant vs. LHP - Bryant has been a notoriously great hitter against left-handed pitching pretty much since he came into the Majors. This season has been no different as through his first 49 plate-appearances, he has a line of .429 AVG .510 OBP .976 SLG with 6 homeruns, 5 doubles and an OPS of 1.486. This should translate to some impressive ratings against lefties in The Show and with 116 contact and 95 power, I'd say that he's where he should be.
Bryant vs. RHP - While we've shown that Bryant is a well-known lefty-killer at the plate, his career numbers versus righties come in a bit worse, but still overall impressive with a career total batting-line of .275 (AVG) .371 (OBP) .488 (SLG) and an OPS at .859. His 2021 season is sitting at a nearly identical .282/.367/.473 line, so with 70 contact and 69 power versus right-handed pitching you're probably thinking that there's no doubt about it, SDS messed this one up. Well, let me show you Bryant's 2020 stats versus RHP: In 112 PA / 103 AB, Bryant put up a batting line of .184/.250/.340 with an OPS of .590 after only hitting 4 homeruns the entire season (with zero vs. lefties) and you begin to see why Bryant's ratings versus righties remain a bit subpar.
Was 2020 a small sample size? Absolutely. Should SDS weigh that against Bryant so heavily? No, I don't think so. But will they? Yeah, more than likely they will until he sustains the success he has been having this year. While it has been said that SDS goes by a "three-year average" against the backdrop of a player's career, 2020 was roughly about one-third of a usual full-season so it's possible that 2018 numbers are still creeping into the weighted statistics that go towards a player's ratings in the game right now. If that's the case, Bryant also struggled in 2018 with a batting-line versus righties of .244/.363/.386 and an OPS of .749.
I think all of that data kind of explains why Bryant's overall hasn't gone up to where some folks were thinking it would by now. It's exactly why when I did my research when doing my investments for the 5/28/2021 Roster Update, I didn't buy any stock into Kris Bryant. That said, if he continues at his current pace, he will no doubt be a diamond before long. I just think SDS wanted to see a bit more before pulling the trigger, especially with five new Live Series diamonds being made in this update. Hopefully this provided you with some comfort and understanding, and moving forward I would suggest that you keep this set of standards in mind whenever you're projecting who will go up in the future.
As for anyone who invested in a large quantity of Kris Bryant, I think the obvious thing to do is just hold steady. Bryant is a special player and the further he gets away from his 2018 and 2020 struggles, the more you'll see Bryant return to his past status of being considered one of the best players in the sport today, both in the media and in The Show itself.