Forsberg: Which path should red-hot Celtics take at trade deadline?

What a difference a month makes.

Thirty-four days ago, the Celtics endured a head-slapping national-TV collapse against the New York Knicks. In the aftermath, we wondered if Boston would be better served to take a step backwards and embrace being a potential lottery team with the goal of a more consistent future.

The Celtics are 13-4 since that day. They own an NBA-best net rating of plus-13.9 in the 17 games since that loss. That’s nearly double the next closest team (Denver, plus-7.7).

After Tuesday night’s thumping of the Brooklyn Nets on another national stage, the Celtics have wiggled into a virtual tie for the sixth seed in the East with the Toronto Raptors. The Celtics are closer to the No. 1 seed (4.5 games) than they are to dipping out of the play-in bracket (5.5 games up on 11th seeded Washington) with 26 games remaining in the 2021-22 regular season.

Boston’s staggering 28-2 run to open Tuesday’s game left us a whole bunch of time to ponder what might happen in advance of Thursday’s NBA trade deadline.

Forsberg's Mailbag: Luxury tax, trade buzz and 'Schroderfreude'

The team that we once thought should embrace being sellers has now shown enough over the past month to suggest they might want to entertain all avenues to solidifying a bench that has been one of the few negatives in a dazzling stretch in which Boston has imposed its will on inferior competition.

It’s fair to be slightly skeptical given the way Boston’s numbers are juiced by lopsided wins against bad teams. We certainly yearn to see how they fare in the fourth quarter of a close game against a quality opponent. But beggars can’t be choosers. The Celtics needed a solid 15-game stretch to inspire confidence and they’ve produced that.

The lingering question: Does this recent surge change any of Brad Stevens thinking before Thursday's deadline?

Are the starters untouchable?

With Marcus Smart injecting new pep into this offense and Robert Williams blossoming into a superstar in his role, we’ve maintained that the team should not tinker with its Core Four. The tougher question is whether the team would ponder using Al Horford’s big-money deal to make a sneaky deadline splash.

Our buddy Ryan “Dangercart” Bernardoni, whom you might have heard offering elite cap-crunching analysis on Celtics Talk podcast in the past, sent along this query for this week’s Celtics Mailbag. It made us think so hard that we stashed it for this column:

The ideal for Al Horford's contract is probably that he gets traded this offseason as the salary matching for a star but let's take that off the table as "unlikely."

Your options are to keep him through next season at $26.5 million, waive him in the offseason to save $12 million, trade him now with an asset for an expiring to clear all the money next year, or trade him now with 2+ assets in a "buy" move.

Which do you choose? Has your answer changed in the last two weeks?

The Celtics starters have been chewing up and spitting out competition. For the season, the Smart-Williams-Jayson Tatum-Jaylen Brown-Horford combo has a net rating of plus-29.6 with an impossibly low defensive rating of 87.9 over 265 minutes of play. 

Not only is that the NBA’s best five-man lineup among any of the 24 quintets with at least 200 minutes, but no other team is even close in terms of defensive rating. Hone in on the 11 games since that January 6 loss in New York and the Celtics’ net rating spikes to plus-41.1 with a defensive rating of 82.3.

The starters have been an absolute buzzsaw despite the fact that Horford hasn’t shot the ball well all season. Horford is shooting an impossibly bad 19.5 percent on all open 3-pointers (4-6 feet of space) and a meager 32.1 percent on all wide-open 3s (6+ feet of space), per NBA tracking data.

It’s left us, at times, pondering whether the first group could benefit from having another shooter with that group in Horford’s place. Using data from Cleaning the Glass, which eliminates all trash-time possessions, here’s a look at the production of the Core Four and then a focus on the various fifth player they’ve paired with.

The results are pretty much what your eyes tells you: The Horford group lags a bit on offense but are an absolute juggernaut on defense. Subbing in Grant Williams or Josh Richardson provides a noticeable spike in offensive output, albeit in very small samples.

Two weeks ago, we would have been open-minded to a potential Horford deal. The Celtics could seemingly shuffle Grant Williams -- or any acquired player -- into a starting role and not see a pronounced dip in overall efficiency. In fact, the offensive boost might aid a team with some consistency woes on that end of the floor.

But what’s become obvious over the past couple weeks is that Horford’s presence on the back line has been key in allowing Robert Williams to emerge as a game-changing defensive presence. Until the Celtics can find a Horford-like presence on the back line, it better serves a defensive-minded team to have him start each half alongside Robert Williams. Moving Horford chips away at the identity of this team as a defensive-minded bunch.

Consider this: When Rob and Horford share the floor, the Celtics have a defensive rating of 98. Without Horford on the court, the defensive rating jumps to 104.1 -- still a very solid number and a mark that would be second in the NBA behind only the Golden State Warriors (103.4) if maintained. But Boston is just a defensive menace when those are together.

Boston’s best trade acquisition might be any sort of hot tub time machine that can get Horford back to shooting anything close to league average or better on 3-pointers.

It’s still tempting to ponder potential Horford deals. When the Celtics were more future-focused, we wondered if Toronto might entertain the idea of taking on Horford and an asset in exchange for Goran Dragic and Precious Achiuwa. Boston cleans its books for the summer and gets back two serviceable pieces. That both teams have surged in the standings and might battle for No. 6 in the East has erased some of those thoughts.

We've also pondered if you could move Horford and assets to Sacramento in exchange for Harrison Barnes but there might be better ways to utilize Horford’s money for salary-matching in the offseason.

It skirts Ryan’s question, but ultimately, in the absence of a slam-dunk "buy" move, the most prudent path forward is to keep the starters intact this season, tinker with the bench, and figure out Horford outside the calamity of the deadline.

The Celtics likely only get one swing at adding another impact talent by utilizing some combination of Horford and their future first-round picks, so they’ve got to make the most of it. All while trying to figure out how to get a younger version of Horford on the roster as well.

Diving into the tax

Given their collection of trade exceptions, the Celtics do have an ability to more easily add impact talent that sellers might yearn to purge. The deterrent, of course, is the luxury tax and Boston’s desire to stay under it this season. We tackled those reasons earlier this week in the mailbag.

Because Boston stayed out of the tax the past two seasons, there is some merit to the notion that paying the tax this season wouldn’t be the worst thing. Repeater penalties only start when you’ve been in the tax three of the previous four seasons, which means Boston is safe from stiff repeater penalties until at least the 2024-25 season. A new CBA and television money could radically alter team spending by that point.

The wild card here is the rebate that all non-taxpayers will receive this year thanks to the historic splurges by teams like the Nets and Warriors. Barring the sort of addition that ensures Boston is a legitimate and surefire championship contender, we simply cannot see the team paying the tax, as enticing as it may be after the recent progress.

Tinkering with the bench

Are there any moves Stevens can make at the deadline (without utilizing a starter) to bolster a bench that has routinely fumbled the baton the past month? 

With an ability to get below the tax by simply paying a team to take on some end-of-the-roster flotsam, the Celtics should hold firm on trying to get a desirable asset from any team bidding for Dennis Schroder. 

NBA trade rumors: Are C's holding out for better Schroder deal?

That said, nothing about the production of Schroder/Richardson/Grant Williams reserve lineups (minus-5.3 net rating in 624 possessions, per Cleaning the Glass) suggests the team can’t find a serviceable replacement if Schroder departs. Payton Pritchard lineups with Richardson and Grant Williams have really struggled but in a tiny sample that could resolve if Pritchard saw more consistent reps.

The Celtics certainly could benefit from having at least one more appealing bench option who Ime Udoka is willing to lean on. The question is whether it’s worth moving someone like Romeo Langford or Aaron Nesmith for a more established player when that player might not change the trajectory of the season.

Every time we convince ourselves the Celtics should make a push for a Frank Jackson- or Ben McLemore-type to add some bench shooting, we wonder if it’d just be better to give those reps to Langford and Nesmith with hopes you figure out what you’ve got.

Ultimately, if the Celtics can clear a roster spot and get far enough below the tax, there could be more intriguing options to add in the buyout market, especially if the promise of playing time might entice a veteran player that doesn't race to join a more surefire contender.