The Boston Celtics won Game 3 against the Cleveland Cavaliers without Isaiah Thomas and put up a good fight in Game 4 on Tuesday. That followed a 46-point loss in I.T.’s final game of the season. With the Celtics selecting No. 1 in the 2017 NBA draft and Markelle Fultz at the top of just about everyone’s board, the logic leads to a natural place. The Celtics’ future lies with Fultz and not Isaiah, right?

Tim Cato laid out the issue on Monday. Isaiah will be a free agent in 2018. He is a valuable trade commodity right now due to his meager salary ($6 million) and All-NBA status. He will be 29 years old when he hits free agency, and paying small guards $30 million or more per season — as I.T. will command as an All-NBA performer — is usually frowned upon.

The thinking goes that the Celtics should move Isaiah for value now and build around Fultz, Jaylen Brown, and the Nets’ 2018 first-round pick (likely to be a good one), while staying competitive with Al Horford, a potential max-salary pickup in 2017, Jae Crowder, and some combination of the other role players and defenders currently on the roster.

Based on how Isaiah finished the regular season and performed through two-and-a-half playoff series, and given our growing understanding of his close relationship with Fultz, the right path for the Celtics might be to do nothing.

Here’s why.

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Fultz’s affordability can offset the expense of Isaiah

It is a given that I.T. will be massively expensive beginning in 2018-19. He has yet to sign a truly big NBA contract, and he has gotten better every season. Barring a drastic regression or a serious injury, Isaiah will enter 2018 free agency with several teams willing to offer the max. He’s going to cost Boston a lot.

You know who won’t cost Boston a lot no matter how good he is? Markelle Fultz. The rookie scale has risen markedly in the new collective bargaining agreement, but the No. 1 pick is still only set to make $7 million next season. (“Only,” says the All-NBA guard making $6 million.)

High-performing players on rookie scale deals typically outperform their contracts by $10 million or more. If Fultz is as good as we think, by 2018-19 the Celtics could be getting high-level production from a player making just 7 percent of the salary cap. (Superstars earn 30-35 percent of the salary cap at market.)

The affordability created by having high-level rookies like Fultz, Brown, and perhaps another 2018 draft star allows you to overpay others without triggering punitive luxury taxes. The cushion created by Fultz overachieving his contract can pad the space for Isaiah if he underperforms his deal.

There’s only a logjam for one year

Part of the reason we hear so much about moving Isaiah is that Boston also has Avery Bradley (very good) and Marcus Smart (quite interesting). Does a team need four guards that good when there are holes to fill up front? Probably not, but they do play a lot of multiple-guard lineups.

It isn’t as if Bradley or Smart are locked up long term. Smart is finishing his third season and is on schedule to be a restricted free agent in 2018. Bradley will be an unrestricted free agent in 2018.

Moving Isaiah almost forces you to pay Smart and/or Bradley (or another guard) big dollars to ensure Fultz has help. Would you rather pay Isaiah $30-$35 million, Bradley $25-$30 million, or Smart $20 million? You might pick Bradley — defense and shooting, it’s a hard-to-beat combination — but it’s really preference at that point. The bottom line is that none of the three major incumbents is going to be cheap in a year.

Fultz projects as a killer shooter and defender. Fitting him in with an elite scorer in Isaiah and an idiosyncratic cannonball like Smart could be the best move. Bradley would have strong value on the trade market, too: Every team could use him at the $8.8 million he’s due in 2017-18. Plus the restricted tag on Smart could help keep his price down and ensure Boston has an opportunity to match.

The Celtics don’t really need to make this decision now, though. Boston isn’t so hungry for assets that moving one of the guards before the season is required. The front office can put off a decision on which to pay until the February trade deadline or even until free agency. As long as Boston commits early to Isaiah in July 2018 and doesn’t renounce Smart, the worst that can happen is that Bradley walks for nothing. You can survive that.

The upside to keeping them? Another really competitive season and, perhaps, better luck against the Cavaliers in the playoffs.

Stop betting against Isaiah Thomas

Has a single bet against Isaiah ever paid off? We’re concerned a team as good as the Celtics can’t get further with Isaiah because of size, neglecting the fact that just about nobody believed Isaiah would be anything more than Earl Boykins 2.0 in the NBA. He made All-NBA. He had one of the most prolific scoring seasons ever. Not for a little guy. Not for a No. 60 pick. For anyone.

Stop betting against Isaiah Thomas. You’re just going to lose.

Betting against Isaiah is a terrible business to get yourself tangled up in. It’s not like he’s entering his late 30s and the league is embracing a style that rewards length above all else. The modern NBA rewards speed (check), relentlessness (check), shooting (check), and vision (three-quarters of a check). It rewards length on defense, and that is a problem for Isaiah and the Celtics.

But the relative defensive weakness of their point guards hasn’t stopped the Warriors or Cavaliers from winning titles. Isaiah is smaller than Kyrie Irving, but is he any worse a defender? That’s doubtful. Stephen Curry has acquitted himself pretty well in recent years, but he still gets picked on (including by the Cavaliers). It happens. You trust Brad Stevens and a roster of grit-faced maniacs like Smart, Brown, and Crowder can survive it.

If you think Boston needs to move Isaiah because he won’t live up to expectations with a fat contract and a new co-star, you’re ignoring every lesson Isaiah has taught us. Stop betting against him. You’re just going to lose.