The Houston Rockets believe officiating in last season's Western Conference finals cost them an NBA championship, and in a report since sent to the league, tabulated the net result of 81 potential missed calls and non-calls in Game 7 of that series between Houston and the Golden State Warriors, according to the report and an accompanying memo, both of which have been obtained by ESPN.

"Referees likely changed the eventual NBA champion," says the memo, addressed to Byron Spruell, the NBA's president of league operations. "There can be no worse result for the NBA."

The Rockets never actually sent the memo to Spruell, because they ended up communicating its messages -- including that they believe officiating cost them the 2018 title -- during in-person meetings with league officials, according to multiple league sources.

They did present the league with their analysis of Game 7. As first detailed by The Athletic after Golden State's controversial Game 1 win in the conference semifinals Sunday night, the Rockets' analysis uses the NBA's own official interpretation of the officiating in that Game 7.

The full report obtained by ESPN lists 81 total calls, non-calls and violations. It concludes that those 81 instances cost Houston a total of 18.6 points in that game.

In its own reports, the league does not attach point values to missed calls and non-calls.

"As we told the Rockets, we do not agree with their methodology," Mike Bass, an NBA spokesman, told ESPN on Monday.

The league provided Houston with what is essentially a full-game version for Game 7 of the last-two-minute report it releases after close games. The report lists incorrect calls; fouls and violations that should have been called but weren't; fouls and violations that would only have been visible, according to the league, with enhanced video review; and uncalled "potential infractions" where the league cannot come to a definitive conclusion on whether a foul was merited.

The Rockets appear to have incorporated all such instances in the report, including those that benefited the Warriors. For instance: with about 6:10 remaining in the first quarter, Stephen Curry drove on the right side of the floor. Gerald Green, the Rocket defending Curry, placed his right arm on Curry's hip as Curry rose for a layup. There was no call. The NBA flagged it as a "potential infraction" -- inconclusive, according to Houston's analysis. The Rockets counted that as a mistake that cost the Warriors 1.8 points -- a figure that appears to have been derived from Curry's career free throw percentage.

Similarly, the Houston report flagged an uncalled foul on a James Harden missed layup, but the Rockets retained control of the ball and scored; Houston in its analysis counted that as a net benefit to themselves of 0.3 points -- the difference between the actual basket they scored and the expected value of two Harden free throws.

The Rockets attached such point values in every instance in their own analysis. With about 10:40 left in the third quarter, Eric Gordon lost the ball when he dribbled it off Curry's foot. In the game, it was a live-ball turnover. The league deemed it a "potential infraction" kicked ball on Curry, according to Houston's analysis -- meaning it might have been a kick, but there is no way to tell conclusively. The Rockets counted that as 1.1 points lost, using what appears to have been an estimate of their average half-court points per possession, according to league sources. (They used that 1.1 figure for all such plays that ended Houston possessions.)

Another: With about 5:05 remaining in the third quarter, Trevor Ariza attempted a runner from just outside the restricted area and made contact with Curry, who tried to draw a charge. No call was made. The league's report flagged that as another inconclusive "potential infraction," according to Houston's analysis. Houston counted it as 1.7 lost points -- again using Ariza's free throw percentage.

With about 8:55 left in the third quarter, Kevon Looney rebounded a Klay Thompson missed 3-pointer. As Looney went up for a putback, Gordon made some contact with him that went uncalled. Looney missed. Looney jumped to try to tip the ball in, and Harden leaped to block Looney's shot -- making some contact with Looney's arm and upper body. Again, no call was made. The loose ball ricocheted to Curry, who passed it to Kevin Durant for an open 3-pointer which went in.

The league cited Harden's attempted block as a potential infraction -- a possible foul, but one the league could not say conclusively was a foul even upon review, according to Houston's analysis. Houston concluded that the non-call cost them two points. Had the officials called the foul on Harden, Looney would have gone to the line for two shots. He is a 61 percent career free throw shooter; Houston attached an expected value of one point to a Looney two-shot trip to the line. But the foul was not called, and Durant hit a 3-pointer -- two more points than the Warriors would have been expected to score, under Houston's accounting, had the officials whistled Harden.

Houston found the biggest negative impact on "landing spot" fouls on Harden 3-pointers -- the same calls that caused an eruption of controversy after Sunday's Game 1, when Harden went to the floor on several attempted 3-pointers. Some of those appear to have been uncalled fouls, according to this description Sunday night from Joe Borgia, the NBA's senior vice president for replay and referee operations. But Borgia said Sunday referees were correct in not calling a "landing spot" foul on Draymond Green's challenge of Harden's potential game-tying 3-pointer in the final seconds; Harden jackknifed his legs forward, Borgia said, invading space to which Green was entitled. (The last two-minute report, released Monday afternoon, confirmed Borgia's analysis.)

The report from last year's Game 7 cites uncalled "landing spot" fouls, including a missed Harden 3-pointer with about 3:40 left in the second quarter on which Jordan Bell leaped into Harden's landing space. The referees did not call a foul, but the league subsequently concluded they should have, the Houston report says. (The league indeed deemed that a foul on Bell, sources say.)

In their memo -- which, again, the Rockets did not end up sending because they communicated its message in person instead -- Houston recommended adding a fourth on-court referee, and that the league make full-game officiating reports available to every team for every game. They also claim a trip to the Finals would have netted at least $20 million in additional revenue.

The Rockets also argue in their memo that veteran officials "exhibit the most bias against our players."

"The reason we are in this situation," the memo says, "is the efforts made to improve the referees have been too slow, not extensive enough, and have been held back by entrenched referees who are resisting reform." The Rockets recommended that referee assignments in the postseason should be determined "exclusively" by call accuracy without regard to experience level.