NASCAR's postseason is complicated and often controversial. Deep-coded radio calls and hidden alliances have now further compromised the competition's fairness during the playoffs. During last Sunday's Round of 12 elimination race at Charlotte Roval, some teams used short phrases on the radio to pass quick instructions.Haas Factory team No. 41 Ford driver Cole Custer was told to "save tires" late in the race. That radio instruction could have, in all probability, functioned as a veiled order to avoid passing Logano, in the No. 22 Ford. Especially since Custer never challenged Logano after his spotter nudged him to stop without spelling out any plan.Alex Bowman was similarly told to "take care of" his tires while chasing fellow Chevy driver Ross Chastain, which many interpreted as a suggestion not to pass.These incidents repeated the controversy from last season's Martinsville race when teams received heavy penalties, including nine suspensions, $600,000 in fines, and stripped points. The body reviewed radio communication and decided that Chevrolet and Toyota teams appeared to coordinate blocking or slowing to favor playoff drivers. The sanctioning body acted when the interference was obvious. Now teams have found a gray zone of coded talk of "save tires", "nice and easy", and "watch your lines".It is also unclear whether this radio talk, which nudges a driver to back off, is manipulative or not. According to the sport's managing director of communications, Mike Forde, NASCAR reviewed radio communications but decided they did not meet the threshold for penalties.However, that decision leaves room for uncertainty: Can teams now use these coded calls freely?In the Xfinity series, NASCAR also warned two teams for discussing other cars' points on the radio during the Charlotte race.Did NASCAR change rules about race manipulation and make some incidents legal?During the final laps of the Bank of America Roval 400, Ross Chastain wrecked Denny Hamlin to beat Joey Logano and get the final playoff berth for the next round.But if Hamlin never passed Chastain, both drivers would have been in a better position, having eliminated Logano, the defending Cup champion, from the playoffs. Also, the Trackhouse Racing driver's aggressive move, if successful, would have improved the championship hopes of many playoff drivers.Moreover, Hamlin could have also decided not to race aggressively against Bubba Wallace during the Round of 12 race at Kansas last month, thereby giving his team, 23XI Racing, a guaranteed spot in the next round of the playoffs. He was way ahead in points to make it to the Round of 8 himself, and a top-5 result would have been enough.But would these incidents have broken NASCAR's rules on manipulating finishes?Earlier this year, NASCAR revised its "performance obligation" rule and removed the phrase "manipulate the finish positions". Now it reads:"Any member who attempts to improperly influence the outcome of the event or encourages, persuades or induces others to do so shall be subject to penalties. ... Prohibited actions include, but are not limited to, intentional planning or conduct that prioritizes objectives other than achieving the best possible competitive result for their team."Certainly, by not passing Chastain, Hamlin would have only acted in his best interest in the playoffs. However, it is still unclear if "the best possible competitive result" applies only to a race or the overall championship standings.