Yes, there are many factors that go into choices like these.
The keeping of as many options in the system for as long as possible may be more important than the extra year of control thing. Anthony, Campbell and Mayer offer great depth to the ML roster without needing to be on the 40. That's like having a 43 man roster. Players who signed minor league deals, and can be stashed in AAA without having to expose the to waivers have real value, too. Teams often choose lesser players to be on the 26, because they have no options or because choosing a non 40 man player to make the team would involve moving someone off the 40 and taking away an option.
Now, we have about 3 pitchers who can be added to the 60 Day IL. That could give us a 2 month benefit of adding someone we need, but we probably will only do this for players we want on the 26 or who we might lose, due to an opt out clause, or who may need to pass through waivers. These are not always the best non roster players, but they are good enough to not want to remove from the chocies Cora & Brez have.
The level of ML readiness is always up for debate, and some seem to think they know who is ready and who is not, better than Brez & Co. There are also various levels of ML readiness- like ready on D but not on O, or this kid might need a lot of time to adjust, but he looks ready, and on a team looking to compete, "time to adjust" could mean losing a game or two. Waiting to promote may or may not work out, but there are always questions. How good the player(s) you have already matters, too. We see a lot of various opinions on how good a DHam-Romy platoon is at 2B. Some just plain do not like platoons. Some think 2024 was a fluke for both DHam & Romy, despite the fact that they brought a stability to a position that has really sucked for 2 seasons, and not been very good for over 5 seasons. Is the step up, if it turns out to be that, worth adding Mayer or Campbell to the 40 & 26, instead of someone else, or instead of holding off, in case a key injury forces another need for a different player addition.
The situation with Anthony has several factors at work, too. A Duran-Rafaela-Abreu OF looks to be one of the best defensive OF's in a long time. Ref vs LHPs is one of baseball's best split batters, and offers relief to Abreu, who has struggled mightily vs lefties out of the gate. Yoshida may not be capable of playing OF, but in Fenway, LF is often used to hide a DH-only type player at that position. He is depth, whether we like the idea or not. Romy and DHam can play OF, for a short time. Adding Anthony looks like an almost sure upgrade, but the word almost is key, and losing other options to add him, might comeback to bite us. Do we bench a GG OF'er who kills RHPs (Abreu?) Do we bench a kid like Rafaela who seems to have immense potential? We are not benching Duran. (I keep repeating that Ref needs to start every game vs LHPs, but not everyone agrees.) How sure are we that Anthony will be much better than Rafaela or an Abreu-Ref platoon in 2025?
It's a risk-reward choice.