Personally, I don't think it's far-fetched to believe that this team as constituted is a .500 or slightly above team with the addition of Rondo.
You say that you think Ainge will be a "seller" at the deadline. I am wondering what you think he will be looking to get back on those sales? Are you implying that he will be selling off players with the sole or primary purpose of getting worse in the short term?
1. Re: Rondo
It is well established that it takes players up to a year once they've returned from a knee injury to get back to where they were prior to the injury. So I think it's reasonable to expect that Rondo is not immediately going to be quite the star-caliber player he has been.
On top of that, I think that Rondo's return will force the team to adjust to playing off of Rondo instead of playing their current style, which involves a more egalitarian approach on offense. A number of the players currently in the rotation have never played with Rondo before, so there won't be any chemistry there at all to begin with. That will take time.
Rondo's return will force some players who are currently doing quite well to change roles. How well will Crawford play once he's forced back into a reserve role? Will Avery still have such confidence offensively when he doesn't have the chance to take so many dribble pull-ups from mid-range? Where will Lee fit in? What impact will Wallace make now that his point-forward role is not as necessary?
Furthermore, I view Rondo as the type of player whose ceiling is raised or lowered depending on the players that surround him. His passing options will be limited on this team with an utter lack of elite finishers. Sullinger is the only thing approaching a reliable offensive option. Green comes to mind, but Green has actually been worse playing off Rondo in the past.
In any case, I think it's far from a foregone conclusion that the team is suddenly going to get better as soon as Rondo returns.
2. Re: Seller Danny
I believe Danny should (and will) look to trade Bass, Lee and Crawford to any team that will give up a second round pick and / or an end-of-the-rotation young player plus an expiring contract or two. I'd add Wallace, but unless it's for an even bigger and more putrid contract, I don't see anybody in the league trading for him.
Bass especially has played quite well this season, and there will be teams that could use his services. I think the opportunity to sell high will be there, and I expect Danny to take it.
Significant return value not necessary; it's all about clearing the deck, for cap purposes and also to free up playing time for young guys.
Re: Rondo
It takes players "up to a year" to return to form? So, that could be within two or three weeks, depending on how well they respond, right?
I happen to think that this roster is full of guys who will benefit from having a primary ball handler to take the pressure off them. We have one of the very worst assist to turnover ratios in the league. Rondo's return should up those numbers to respectability, which I think will do wonders for the offense.
Avery Bradley played the best basketball of his short career as a two guard next to Rondo. Having the ball in his hand to create his own offense is not his best role. I thought everybody was in agreement on that. Lee is a prototypical off the ball player, as well. I contend that Gerald will be much more effective alongside Rondo as well. His job will be to get in passing lanes, create havoc, and run. He will be rewarded. I'm sure Jordan will lose minutes, but hopefully he will be able to stay effective as a scoring back up to Rondo.
Also, I believe that Stevens has kept Rondo in mind while creating this offense. Rondo's return will help the running game, which looks like it is one of Stevens' main focuses. The strategy to have the bigs spread the floor to beyond the three point line will open up the lane for a player like Rondo and make it even easier for him to pick defenses apart.
In short, this team is clamoring for a player like Rondo right now, someone who can get into the lane and create offense, making it easier for everybody else.
Re: Seller Danny
Crawford is an expiring contract. I don't see what trading him in for another expiring contract saves us.
Bass expires after the following season.
Lee is locked up for three seasons including this one, but his contract is hardly going to represent an albatross at about $5million a year.
I'm not saying Danny shouldn't or won't make any moves, but I don't see it as anything approaching a necessity in the immediate future. If the right deal comes make it, but there's no need to make trades just for the sake of getting rid of guys.