Pat Riley has to be a bit worried right now. The Miami Heat have been trying to come up with a trade package that will lure either Kevin Durant or Donovan Mitchell to South Beach, but it appears that the Brooklyn Nets and the Utah Jazz have just not been amenable to whatever Riley's front office has on the table.

Reigning Sixth Man of the Year Tyler Herro appears to be the centerpiece of any potential trade package for the Heat. However, it seems that there hasn't been a ton of interest in the highly-touted 22-year-old. In this respect, NBA insider Zach Lowe of ESPN reports that the Heat have made little progress in the trade pursuits for Durant and Mitchell:

[Tyler Herro] has reached this strange point just as he becomes the key veteran in any potential Miami Heat trade package for Kevin Durant, Donovan Mitchell, or whichever star becomes available next. The Heat so far have not gotten much traction on either front, sources say, but they are still trying and can never be counted out.

At this point, it's becoming increasingly plausible that Kevin Durant ends up staying in Brooklyn. The Nets have slapped an extremely high price tag on their cornerstone superstar, and no team in the league seems to be willing to meet their lofty demands.

On the other hand, the New York Knicks appear to be the frontrunners to land Mitchell. It's not a foregone conclusion just yet, but the Heat are at a clear disadvantage at the moment.

As Lowe's report states, however, these rather discouraging updates are by no means going to prevent Riley and the Heat from going after both superstars. It ain't over until it's over.