Admin Notes
A few quick comments:
1. Changing the list of available players while recruiting is in progress is a non-starter. Coaches rely on the fact the player list is steady while preparing their orders. So, the list of players would be limited to those cut prior to season initialization, not afterwards. This would include players cut during the offseason (though there are very few) but not walk-ons cut after initialization as that would punish coaches who got their invitations sent early.
2. Current gameplay balance is based on the current distribution of player talent within the recruiting pool. If we were to change the construction of the recruiting pool by adding, say, CC or DC and higher, we would have to prune the existing recruiting pool of about the same amount of talent and generate more F/F "non-transfer" type recruits. So, I'm not sure there would be any impact from this.
3. As with the current transfer system, there would be no prohibition against recruiting your own transfers if this change were made. This has never been needed as that letting someone transfer rather than giving a scholarship and then trying to recruit the same player would be a poor use of recruiting points.
So, overall, I'm not sure what this would accomplish from a gameplay standpoint. Willing to hear additional thoughts given this has been a fairly popular suggestion, but I would need to be convinced as rebalancing the recruiting list in light of what is probably a small number of additional transfers seems to not be a good use of time.

Comments
Stephen Thompson (Apr 21 04:52:01 2020 ): My only question whether there should be a minimum talent to make the transfer portal. Nobody wants all of the F/F walks that the tier 3 teams cut in abundance.
Dagger Dave DD (May 30 09:47:20 2020 ): I would only agree if the cut players were C/C rated or better. Otherwise, no. (Too much junk in the trunk.)
Pythagoras A (Aug 3 17:05:06 2020 ): I also agree with the point of not sending all of the FF players there as well. FD, DD, and above can still be useful for tiers 2 and 3.
Daniel Hilsgen (Jun 5 14:20:07 2022 ): As long as the cutoff doesn't add too much junk to the trunk.
Eric O (Feb 2 11:56:53 2023 ): Dave, I would suggest DD as the cutoff, not CC. There are plenty of DC recruits that are immensely useful to a Tier III or even a Tier II that I'll cut as a Tier I. Updating - I think DEL is out of balance with real life anyway. The most recent season of CBEL, the ACC rating as a whole was 1.581. In dolphin ratings back to 2002, the highest conference rating was just over 1.4. Since 2002 there have been two seasons, total, where a conference with an auto-bid was worse than -1.4 (2 years of the SWAC and one year of the "Great West" which was never a real conference and never had an automatic bid). This year in CBEL there were two. Many, if not most, years of the RL Dolphin ratings, the worst conference was roughly -1.2. Half of Tier 3 conferences were below that mark in CBEL this year. I get that it'll never be a perfect replica of real life, but the difference between a decent Tier 1 and a decent Tier 3 is significantly more in CBEL than in real life. And while I'm not doing a deep dive on other college sports today, I think it would show similar results. I don't think we need to go all in trying to replicate the RL transfer portal, but the team quality bell curve is smoother in real life than it is in CBEL and I think this would help nudge things in that direction.
Gregor Ellis (Oct 13 19:51:00 2023 ): I agree fully. This shouldn't distort significantly the talent pool distribution created each season as most of the cuts are from the walk-ons pool anyway.