Otto Porter was sitting on a stanchion by the sideline at TD Garden in Boston a little more than a month ago, reflecting on the kind of year it had been, easily the best of his career.

“I put in a lot of work, I just wanted to get better and better at the things I could do to help this team win,” he said. “I think the shooting the ball, seeing it go in the net has been a help. I worked on my mechanics a lot, making sure my body is squared up to the goal, making sure my release is good each time. It is something I have focused on.”

It worked, and his timing was impeccable. Porter is a restricted free agent this summer, which means he will be eligible for a major pay increase, from the $5.9 million he made this year to something in the range of $25 million per season. He is the third option on the floor, but in the Wizards’ books, he would be at the top of the food chain, ahead of All-Stars Bradley Beal and John Wall.

That is a problem for the NBA, a league whose payrolls are getting increasingly top-heavy. Porter and the Wizards are a prime example.

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It won't be a stretch to see Porter receive a payout of about four years and more than $100 million this summer. There will be another spike in the salary cap, and there will be teams eager to fill their salary space with a versatile 24-year-old who has improved in each of his four NBA seasons — Porter averaged 13.4 points and 6.4 rebounds per game, shooting career-highs from the field (51.6 percent), the 3-point line (43.4 percent) and the foul line (83.2 percent).

Because Porter is a restricted free agent this summer, other teams can make offers for him, but the Wizards have the right to match any deal. Ideally, the Wizards and Porter will work something out quickly, something that keeps his annual salary more in line with that of his teammates (Beal is set to earn $23.7 million next year, and Wall will make $18 million).

But, though Porter went to college at Georgetown and is comfortable in Washington, he has no incentive to give the Wizards a hometown discount.

“If his situation goes past the first couple of days of free agency,” one general manager told Sporting News, “it will cost them because some of these teams that have space and miss out on the players they have in mind to start with are going to move quickly to the restricted (free agents). And Otto Porter is going to be at the top of that list, even at $100 million.”

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The Nets have long been rumored to be willing to pay up for Porter. The Wizards caught a break when the Mavericks traded for Nerlens Noel, another restricted free agent, because Dallas intends to make him an offer in the max range — the Mavs had intended to pursue Porter. League sources suggest the Magic and Sixers will also consider making offers for Porter.

The Wizards have no intention of letting Porter walk, but they’ll have to overpay to keep him. Even if Porter accepts a deal in the range of what Beal makes over five seasons (the Wizards can give him one more year than other teams, so he would make five years and about $115-120 million in that case), the team will be setting itself up to pay its top three players $65-70 million per year. That number will spike when Wall gets an extension.

The salary cap for next season is expected to come in at $101 million, with a luxury tax threshold of $121 million. About 70 percent of their cap, then, will be spent on their first three players. They’re committed to $37 million for Markieff Morris, Ian Mahinmi and Marcin Gortat (possible trade bait), which means six players will put them over the cap and within striking range of the luxury tax.

Here’s the problem for a team like the Wizards, and for top-heavy teams like Washington all across the league: It’s not going to get better. We saw spikes in the cap last summer, and we will see another for this summer. Next year, the projection is that the cap will level off to about $101 million again, with maybe a slight increase. The tax will be about the same, too.

The Wizards’ salaries, though, will not level off. Wall will get his extension, Beal’s contract will bump up by $1.6 million per year and Porter’s will include raises, too. They’ll keep getting a bigger chunk of a stabilized salary cap. Eventually, Washington will have its three mainstays at the top of the salary chain, a few of middle-range contracts below them and a lot of minimum-salary fodder after that.

That’s the future of the NBA. You can afford three guys, and you’ll probably have to overpay them. The rest of your roster? Try crossing your fingers, tossing coins in every fountain in town or perhaps dabbling in voodoo.

Washington is not alone in this problem. The collective-bargaining agreement puts an emphasis on ensuring that the players at the top of the NBA’s food chain are discouraged from changing teams, which usually requires paying them well over what they produce on the floor.

Porter will benefit. But the Wizards will have to handcuff themselves to make sure he does.