A little over a month ago on December 6th, the Cleveland Guardians selected 20 year old Diamondbacks prospect Deyvison De Los Santos (DDLS for short) in the rule five draft. Preston (Steak85) covered that news and the implications a few days later, give that a read if you haven't already.
Despite Brad Keller being a more recent example of a D-back taken in the Rule 5 draft with success at the major league level, putting up three solid season from 2017-2020, Diamondbacks fans instead immediately had PTSD flashbacks. In the winter of 2005, Dan Uggla was also left off the 40-man roster, and subsequently taken by the Marlins in the Rule 5 draft. Uggla would go on to become the first player in MLB history to be selected for the All-Star Game in the same season in which he had been a Rule 5 pick, and the first second baseman in Major League history to hit 30 or more home runs in four seasons.
Dan Uggla (link to bref page, fangraphs) was coming off a fantastic year in the AA level Southern League .297/.378./502 with 21 hrs in 132 games, followed by an impressive .304/.390/.598 with 7 hrs in 29 games in the Fall League. I don’t have wRC+ stats for his MILB stats, but that is a fantastic season in the very pitching friendly Southern league. Newly hired GM Josh Byrnes was apparently blindsided when it turned out that Uggla was Rule 5 eligible, so much so that they tried to see if they could take their own player in the draft. Obviously, it turned out they couldn't draft their own player, and Uggla would be drafted by the Marlins, eventually going on to post 20+ fWAR before hitting free agency.
If the D'Backs could have kept Uggla protected in the Rule 5 draft, they absolutely would have. Now let's compare Deyvison De Los Santos's situation and statistics to Dan Uggla's. De Los Santos is significantly younger than Uggla, so his minor league statistics need to be framed through that lens. However, unlike Uggla, De Los Santos isn't coming off a fantastic season in a pitcher friendly league, it's the opposite. After a succesfull 2022 season where he put up .329/.370/.513 and a 122+ WRC in Visalia, then .279/.307./506 and 120 wRC+ after being promoted to Hillsboro, DDLS put up just an anemic .231/.333/.359 and 83 wRC+ in 10 games for AA Amarillo to finish out the 2022 season. De Los Santos still earned a trip to the Arizona Fall League, but failed to impress there, putting up a meager .219/.286/.328 triple slash line.
De Los Santos would return to Amarillo for 2023, but the results were only slightly better, hitting .254/.297/.431, which amounts to just an 88 wRC+ in the hitter friendly Texas league. Looking deeper into his stats there are some troubling trends. His BB% fell from 11.1% down to just 5.2% and his strikeout percentage ballooned from 20% up to 26%. The only saving grace for De los Santos' 2023 season was the fact that at 20 years old, he is still young for AA. If it wasn’t obvious from all that, I don't think de Los Santos is ready for the big leagues, and from what the Mike Hazen has said, it sounds like the team agrees with my assessment.
DDLS would be repeating AA to start off the 2024 season. Even the best prospects can struggle making making the jump from AAA to MLB, let alone from AA straight to MLB, so its very unlikely DDLS will be able to manage that feat. That's by far the biggest reason why the team made the calculated risk to leave him unprotected; not only does he have to make the jump from AA to MLB, but he has to stick on the Guardians roster the entire season. The Guardians will have to put up with some very bad stretches out of de Los Santos if they are truly intent on retaining him.
To make it even more difficult for De Los Santos, I'm not really sure where the Guardians intend on playing him either. They have DH, 1B, and 3B accounted for, although he apparently he has expressed interest in playing the outfield this offseason. Personally, I would not be throwing a 20 year old rule 5 pick into the outfield for the first time while expecting him to succeed at the MLB level. That doesn't necessarily mean that DDLS will return to the D'Backs organization if he is unable to stick on the Guardians major league roster. One possibility is that the Dbacks work out a trade, which would allow the Guardians to retain him. Either way I'll be monitoring his progress, and by the end of spring training, we should have a better idea about the likelihood of him sticking with the Guardians or not.