I'll resurrect this thread to bring forth some realistic but unexciting options that could fill holes on this roster. Low floor, maybe high potential players depending on who they are. Only considering UFAs, no sign and trades, just players we can have for MLE or less and sign straight up.
For reference the MLE is about 10M for teams not in the luxury tax, about 6M for teams who are over the luxury tax. Even with re-signing Lavine Bulls should remain under the tax as far as I know.
1. Backup big
This is a giant gaping hole, but it'll be hard to get a game changer here with the resources available. You want someone who can defend and rebound, offensive ability is a bonus I think at the MLE and lower level of player. Here's some options
Thaddeus Young - He's old, but he thrived in this system. At 34 he'll probably be more willing to get paid MLE or less. Offense is lacking as far as scoring, but brings a big playmaking component to the bench while being a very solid defender. A pretty decent upgrade over all our bench bigs as of now.
Jalen Smith - A rare two way option at the 4 on this FA list. Did well given minutes in Phoenix and Indiana last year. He can hit the 3 and block shots and decent rebounder as well. Still young so that's a plus. A bit foul prone, but in ~25 mpg with Indiana he provided all we could ask for from a reserve big.
Bol Bol - Absolutely available, can block shots and hit 3s. Actually has a little bit of perimeter skill. Looks like a twig, but that's what makes him perhaps the most realistic option lol. Really low floor, potentially a high ceiling. Worst case he gives as much as Tony Bradley did. Best case, a 3 and D big? With limited options I say why not take a flyer and see what happens, especially if no better options present themselves.
Chris Boucher - I've actually heard him called not an NBA level player by some Raptors fans on Reddit, but again hits 3s and blocks shots so that's better than what we're getting. Approaching 30 so depending on salary expectations might be a reach, but he also had a relatively down year last year compared to the one before so perhaps his value is down enough to be in our range.
2. Shooters
Plain and simple we need more of them. Coby should be the one who really fits that role, but he's all over the place. Matt Thomas fits that role, but he can't get on the court.
Ben McLemore - Not particularly efficient and can't create his own shot (he doesn't have to here), but he's someone you can run plays for to get an open 3. Above average shooter, has some physical tools that he doesn't seem to know how to use properly, can't defend a cone. If he's more consistent than Coby on offense though, that's an improvement. All in all, a pretty realistic option for a shooter, not gonna wow anyone, but fits the role.
Bryn Forbes - shoots over 40% from 3, but lacking a great deal of size. Has shown though he can be an asset as a shooter if given opportunity. Of shooters available, he's probably one of the better options honestly. If we were to punt Coby somewhere else, he could slot right in and we'd probably see an improvement just because of the consistency shooting the ball.
Joe Ingles - Coming off a major injury and in the last years of his career. However, one of the few FAs available who actually has a little bit of size and shoots 40% from 3 for his career. High IQ player as well, always a plus. Due to the injury and age, unlikely to be a good defender anymore so putting him as only a shooter, but if he can recover some defensive ability that's a huge plus.
Mention for the lulz - Carmelo Anthony. He's not really realistic, but the man can shoot.
3. 3&D
The ever elusive ideal role player that every team needs. Troy Brown Jr was supposed to be this, but alas. This is going to be very hard to fill within this FA class
Victor Oladipo - He's actually probably not a realistic option if Miami wants to keep him, but if he's available he's worth a look. Hasn't been super consistent in the playoffs with Miami, but he's still getting his legs under him really and fought his way into the rotation. Really high upside if he's available for MLE or less.
Otto Porter Jr - If used properly and not making a huge salary, we'd have been totally fine with him the first time around. Probably the best SF option available in this role honestly. Again health is an issue, but better than the production we're getting from Troy Brown Jr.
Everyone on this list is flawed and can be argued against, so that's exactly why they were considered. However, they do fit the role and I tried to only consider players that would truly fit the roster as well. Imo there's no one realistically available who's going to vault this team into bona fide contender category, so don't bother with that, just fill some holes on your bench and see if you can hit close to 50 wins with a hopefully more healthy squad next year.
Side note, there's probably also GLeague players that you could take a flyer on (like Bol Bol) but I'm less familiar with them so didn't consider others.