We've never seen anyone rise, or fall, quite like Isaiah Thomas

Isaiah Thomas finally got his tribute video.

Thomas was back in Boston on Monday night as a member of the Denver Nuggets. After last year's planned tribute was stymied - first by Paul Pierce's whims and later by a midseason trade from the Cavaliers to the Lakers - he watched from the sidelines during a first-quarter timeout as the sights and sounds of his two-and-a-half years with the Celtics flashed across the big screen at TD Garden.

In one sense, the moment proved worth the wait; the crowd showered the 5-foot-9 point guard who once entranced them with a deluge of affection that clearly moved him deeply. But as he gazed up with a dreamy, faraway expression at smash-cut highlights showing a now-unrecognizable player doing ungodly things, it hammered home just how dramatically Thomas' fortunes have changed in the 19 months since he departed Boston.

The homecoming celebration, deserved though it may have been, felt strange with the returning hero now a marginalized member of his third team in two seasons. Nuggets coach Michael Malone - for whom Thomas specifically chose the Nuggets this season because Malone was "one of the first guys in this league to love me for who I am" - had already publicly declared that Thomas wouldn't be part of the team's regular rotation down the stretch. Nevertheless, Malone gave Thomas a chance to make his mark on the game, inserting him late in the first quarter for a seven-minute stretch.

It didn't go well.

Looking both nervous and overeager, Thomas went scoreless with a pair of assists. The Celtics outscored the Nuggets by eight points in his minutes, during which he thunked a floater that hit nothing but window, caught front iron on a wide-open three, and stepped out of bounds while looking to attack off the catch from the wing. He sat for the whole second half as the Nuggets pulled away for a 114-105 win.

Regardless of his relationship with Malone, Thomas' integration with the Nuggets was always going to be tricky; they prefer to run their offense through their big men. Denver has gotten terrific guard play off the bench from Monte Morris and Malik Beasley while scratching and clawing and scheming its way to a respectable defense. Where does an undersized, ball-dominant point guard fit into that equation?

The answer was predictable. Thomas has played 10 games since returning from hip surgery on Feb. 13, averaging 7.7 points on .364/.265/.632 shooting with as many turnovers as assists. With him on the floor, the team has performed 13.2 points per 100 possessions worse. The explosiveness and shot-making ability that once allowed Thomas to thrive despite his height have disappeared along with the torque in his hip.

Yet there he was on the video board - the footage not two years old - bombing pull-up threes out of the pick-and-roll, skittering around screens and slaloming his way to the rim, roasting bigs on switches, crossing dudes over, finishing through thickets of trees at the rim.

It was a reminder of how Thomas' skills all crescendoed into that majestic 2016-17 campaign, during which he averaged 28.9 points and 5.9 assists, made 245 3-pointers, led the league in fourth-quarter scoring, and placed fifth in MVP voting as his Celtics finished first in the Eastern Conference. Among the 36 historical instances of player usage rates of 34 percent or higher, Thomas' true shooting percentage that year (62.5) ranks first.

Then came the hip injury, cropping up late that season and growing steadily worse. Thomas' sister, Chyna, died in a car accident the day before the playoffs started. He played through the unimaginable pain of that loss, and the pain in his hip, and the pain in his mouth (after he got elbowed, lost a tooth, and required hours of stabilizing dental work) to deliver one of the most memorable postseason performances ever: a 53-point outburst in a Game 2 win over the Washington Wizards in the Eastern semifinals - on what would have been Chyna's 23rd birthday. Two weeks later during that same series, he produced a 29-point, 12-assist outing to fuel a Game 7 win.

The hip injury ultimately sidelined him in the conference final, and Boston traded him a few months later in a package for Kyrie Irving.

Thomas has played in just 42 games since then. If the end of his Celtics run wasn't heartbreaking enough, we now know those playoff games probably contributed to the irreversible deterioration of his body. We tend to lionize courage in athletes, especially when it manifests as physical resilience. Increasingly, though, we also recognize the need for self-care and self-preservation. Those ideas can be hard to reconcile.

Whether Thomas was fully aware of the risks he was taking has been a matter of some dispute between him and the Celtics. But he's said he doesn't regret his decision to play through everything that ailed him during that 2017 postseason. It was therapy, he's explained.

"At that time I was going through something way bigger than basketball," he said last year after his season-ending hip surgery. "So basketball was the only thing that could really numb that at that point in time. I don't regret it."

Thomas simply never had a margin for error. He couldn't afford to lose even a smidgen of his quick-twitch athleticism, his ability to create separation, his accuracy as a jump shooter. There are few safeguards for a player operating at such a distinct physical disadvantage. Given his inherent defensive limitations, he'd always need to be offensively elite to have a positive overall impact. If anything, the precipitousness of his decline only serves to highlight the improbability of Thomas ever reaching such heights in the first place.

There is a notion of tragedy in the narrative structure we prop up around pro sports, that self-contained universe where we suspend our disbelief and assign everything outsized importance. Then there is tragedy as it exists in real life. Over the past two years, Thomas has experienced inordinate exposure to both. His arc has become something of a cautionary tale, evidence of both the fragility of an athlete's career and of the cold business of basketball.

For Thomas, who's always played with a chip on his shoulder, the famous declaration that the Celtics would need to "back up the Brinks truck" for his next contract didn't so much backfire as become a punchline, shorthand for his unwavering and sometimes misguided self-belief - even if the sentiment was warranted when he expressed it. That dissonance became particularly cruel as his miserable 2017-18 season cost him tens of millions of dollars. He found so few suitors in free agency he decided to sign a one-year minimum contract, joining a team that has since decided it's better off with him riding the pine.

How many NBA players have fallen this far, this fast, while still in their ostensible athletic prime? Derrick Rose comes to mind. But the closest comparison in recent history might be Brandon Roy, who was an All-NBAer and likely one of the Association's top three shooting guards and then out of the league in a span of two years. But Roy was a sixth overall pick, of whom big things were always expected, and he at least got paid. Thomas - the very last pick in the 2011 draft - worked his way to legitimacy, signed a below-market deal, exploded into superstardom, and crashed out just before he could fully cash in.

Roy, for what it's worth, also managed to deliver one last heroic playoff moment before it was all over. Thomas' time to author such a farewell appears to be running out. But he, of course, doesn't see it that way. He still believes he can get back to an All-NBA level, perhaps even with the Celtics. It seems more likely Thomas will be playing overseas than in Boston next season, but his career to date has also been one giant anomaly, so maybe assumptions are pointless.

At the very least, Monday's game provided the opportunity - if only for a moment - to take a break from harping on what Thomas can't do and appreciate what he did.