By just about any measure, the last three seasons have been the best time to root for the Toronto Raptors in their 20-year history. The Vince Carter era was thrilling but brief, and Chris Bosh’s dinos never quite realized their potential. Since 2013-14, however, the Raptors’ winning percentage has hovered around 60 percent, and their efficiency differential has been roughly 3.5 points per 100 possessions — numbers that those previous runs only approached in spurts.

For all that success, however, Toronto has had trouble making any kind of dent come playoff time. As my ESPN colleague Zach Lowe wrote about Tuesday, each of the team’s past two postseasons ended with a first-round exit, and although the Raptors were upset both times — implying they had the talent to potentially go further — 49-win teams don’t typically vie for NBA championships anyway. If this season’s version of the club is basically the same, expecting different results would be irrational.

These Raptors, however, have a secret weapon that their predecessors lacked: skinny Kyle Lowry.

Technically speaking, this is Lowry’s fourth season with Toronto; he even logged the second-most minutes of any Raptor during the failed playoff runs of 2014 and 2015. But that version of Lowry was — how can we say it? — less svelte, and far less productive. By Box Plus/Minus (BPM), Lowry’s 2014-15 season was the worst he’d had in four years. This season, though, Lowry profiles like a top-five player according to the advanced metrics. And his sudden improvement could finally give Toronto the star power necessary to truly compete for a championship.

Lowry’s evolving game

Before this season, Lowry appeared to be on an evolutionary arc many players go through, trading a higher usage rate for less efficient scoring. In his rise as one of the game’s best guards, he’d once ranked in at least the 70th percentile of NBA players in both true shooting percentage and usage. That isn’t an easy thing to do. But last season, Lowry seemed to have surpassed the workload at which he could maintain a reasonable level of efficiency — a situation exacerbated by the banged-up state he found himself in as the season progressed. As a result, his offensive numbers dipped: He settled for more midrange shots and drew fewer fouls; he ran the pick-and-roll less often (and less efficiently); and over the course of the season, he struggled with his jump shot in a way he hadn’t for years.

Although Lowry was pretty clearly not being himself, the Raptors won the Atlantic Division and locked up the No. 4 seed in the East. But the team was also unceremoniously swept by Washington, a series in which Lowry kept a high usage but saw his efficiency completely collapse. This seemed like a bad sign.

Perhaps even more troubling, it was getting harder to find evidence that Lowry — a player with a good two-way reputation — was still among the league’s best defensive guards. Going into last season, he’d ranked up around the 80th percentile of NBA guards in defensive BPM over his career — a ranking corroborated by play-by-play plus/minus metrics and tracking data from Synergy Sports Technology — numbers underpinned by smart, bruising pick-and-roll defense. But in 2014-15, Lowry’s defensive indicators offered mixed messages. Although he still gave the Raptors’ defense a boost while on the floor, the team was also significantly worse defensively than it had been the previous season, and Lowry often looked slow, clunky and, at times, indifferent when trying to fight through ball screens.

This season, Lowry has made course corrections at both ends of the floor. Although his usage continues to grow, his scoring efficiency has bounced back, in part because of smarter shot selection. He’s once again devoting fewer shots to the midrange, allowing his rates of taking threes and drawing fouls to return to their historical norms, and he’s been faster and more aggressive in the transition game as well. On defense, you can really see the effects of Lowry’s offseason weight loss. Last season, Lowry frequently failed when trying to use his strength to fight through screens (both on the ball and off), ceded too many easy buckets on pick-and-rolls and was generally slow to recover when he guessed wrong or his gambles didn’t pay off.

2014-15:

The new, slimmed-down version of Lowry has been quicker afoot and more focused in his pursuit of ballhandlers around and through screens, forcing more turnovers and fouling less as a result.

2015-16:

It’s likely no coincidence that Toronto’s opponents are scoring at a rate of nearly 4 fewer points per 100 possessions with Lowry on the court than they did a season ago. In fact, Lowry’s rehabilitation has been so complete that the Raptors now rank among the league’s top 10 teams at both ends of the floor and he has risen to full-blown MVP candidate status.

You’re only as good as your best player

It’s no secret that there’s a distinct relationship between a team’s championship probability and the quality of its best player, but it takes a truly exceptional player to make a run at a title. In the past, Lowry hasn’t been good enough to move that needle, but this season’s version is inching into the territory where small individual improvements can drastically upgrade a team’s chances of winning a championship.

We’d expect a team being led by Lowry at his previous career-high BPM of +5.9 to win the title about 5 percent of the time; at this season’s +7.2 mark, those odds are doubled, to 10 percent. (Not even Carter in his prime led Toronto with a BPM so high.) Add in a decent supporting cast — and it’s debatable as to whether Toronto has one of those, particularly with DeMarre Carroll on ice, but let’s entertain the notion anyway — and suddenly the idea of a championship parade down Bay Street doesn’t seem quite so pie-in-the-sky.

So this season should be encouraging for Raptors fans, at least by this metric. But after years of watching Chris Paul-led teams underachieve in the playoffs, it’s fair to ask whether this algorithm oversells the title chances for a point guard-driven squad. And as it happens, controlling for the entire skill set of a team’s best player, we found a slight tendency for teams led by players with a lot of value tied up in passing to perform worse in the postseason than we’d expect from their BPM. This could be due to any number of causes — from defenses keying in on passing patterns in a long playoff series to the way a playmaker’s value is only maximized when complemented by other skills (or perhaps it’s just random noise) — but it’s one (albeit minor) reason to consider lowering expectations for Lowry.

Except that this season, Lowry’s game has been extremely well-rounded — he ranks in at least the 78th percentile of all NBA players in scoring efficiency, possession usage, assist rate and defensive BPM. Historically, teams whose best players excel in the first and last of those categories tend to exceed expectations in the playoffs at a rate far greater than any penalty that’s levied against passers.

Of course, all of this presumes that Lowry’s overhauled game is legit. He’s currently 29 years old, an age at which NBA players are typically already on the downside of their careers, not metamorphosing into championship-caliber stars. Also, there was little in Lowry’s preseason CARMELO projection (our statistical crystal ball for NBA careers) to suggest an imminent breakout, aside from the late-blooming presence of Steve Nash on the fringe of his comparables list. An optimistic look at his strongest CARMELO comps suggested that he might pull a Rod Strickland and stay productive into his mid-30s; a less rosy one saw the possibility of flaming out far sooner, like Michael Adams and Derek Harper. So it’s entirely possible that Lowry will regress toward his previous career norms in the season’s second half.

But given the particulars of Lowry’s skill set, and the ways in which he’s corrected his deficiencies of a season ago, it’s also very possible that if his caloric intake doesn’t regress, neither will his output.

The question of whether Lowry’s teammates are good enough to support a championship run is still very much open. And even if they are, Lowry may have timed his improvement poorly, elevating his play during a season with two abnormally dominant teams that are soaking up all the league’s title odds. But Lowry’s sudden upgrade to the NBA’s elite class of players gives the Raptors a superstar the likes of which they’ve never had before. At the very least, they now possess a crucial element that was missing from the team’s recent string of good-but-not-good-enough campaigns.