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Sometimes the best trades are the ones you never make, and last offseason may have been a perfect example for the Boston Celtics.

On the most recent episode of Bob Ryan's Boston Podcast (via CSN New England), ESPN's Jackie MacMullan reported Celtics general manager Danny Ainge was aggressive in trying to acquire an additional lottery selection. Even Isaiah Thomas was considered a potential trade chip.

"[Ainge] was on the phone with everybody from coast to coast, and he was offering everybody," MacMullan said. "That includes Marcus Smart and [Thomas], and anything else they needed to get where he wanted to go. There were no untouchables on that team last year."

In retrospect, trading Thomas—even if Boston acquired a high draft pick—would've been a mistake. Thomas averaged 28.9 points a game and helped the Celtics reach their first conference finals since 2011-12. No player was more important for Boston than the 5'9" point guard.

This time last year, though, the thought of parting with Thomas would've made more sense. While the 28-year-old was coming off his first All-Star appearance, he had yet to truly establish himself as one of the elite point guards in the NBA.

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Thomas' contract was likely a consideration as well. He's a free agent after the 2017-18 season, and after 2015-16, Ainge may have had reservations about whether the inevitable cost to retain Thomas would be worth the investment.

Even now, Thomas' impending free agency is a big question mark for the franchise. The Celtics won the 2017 draft lottery, which presumably means they will select Washington Huskies guard Markelle Fultz.

With Fultz potentially the team's point guard of the future, the prospect of giving Thomas a max deal at his age is a dilemma most teams would love to have, but it's a dilemma nonetheless.

Ainge traded away Paul Pierce and Kevin Garnett, so he almost certainly won't be sentimental when it comes to evaluating Thomas' long-term outlook in Boston.

Speaking to Ryan, MacMullan posited Al Horford is the only untouchable player on the Celtics roster when it comes to potential trades. It will be interesting to see if any trade rumors around Thomas reignite this offseason