Who was most improved Celtic?

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Boston Celtics center Tyler Zeller and forward Jae Crowder each received one vote for the league's Most Improved Player award, which ultimately was given to Chicago's Jimmy Butler.

Those Celtics players were aided by local broadcasters, as Zeller received a first-place vote from TV analyst Tommy Heinsohn and Crowder earned a second-place vote from radio analyst Cedric Maxwell.

The most improved player award is among the most subjective in the league, which is why 30 different players received votes and 23 of those players received five total votes or less in balloting by a panel of 129 sportswriters and broadcasters. One five-point, first-place vote was enough to help Zeller finish tied for 10th, while Crowder tied for 14th.

This got us thinking: Who really was the most improved player on the Celtics this season?

The field for most improved player is typically limited to young players who exceeded previous expectations. With that in mind, we oversimplified the process and examined candidates on Boston's roster and how their Player Efficiency Rating (PER) compared to their career average.

Isaiah Thomas, an in-season acquisition, easily posted the best PER on the team at 22.3, albeit in a 21-game sample after being acquired in late February from Phoenix. Even adding in his numbers with the Suns, Thomas finished with a PER of 20.6, which was still +1.5 above his career average.

Zeller had the biggest jump on the team with his PER of 18.9 being +4.1 from his career average. Some will argue that Zeller didn't so much improve as get a greater opportunity in Boston. But if you compare Zeller's stats from his rookie season -- one in which he actually played more minutes in a similar number of starts and appearances for a rebuilding team -- his numbers spiked despite playing five minutes less per game this season. Most notably, Zeller averaged a career-best 10.2 points per game while shooting 54.9 percent from the floor (this after averaging 7.9 points per game while shooting 43.8 percent in his rookie season).

Jared Sullinger and Kelly Olynyk both made minor strides this season, as well, though both were also limited due to injuries. Jonas Jerebko far exceeded expectations after being acquired at the trade deadline and there's a case to be made that, with a full season in Boston, he could have sneaked into the discussion.

Crowder hammers home how PER might not be the best metric to judge overall improvement. His 14.1 PER with Boston was plus-2 for his career but still below the league average of 15. Crowder's gritty defense and hustle isn't quite captured in his rating and he also thrived with more floor time than he had seen with the Mavericks.

So which player saw the most improvement for the Celtics this season?

One thing is certain: Brad Stevens got a lot more than expected out of much of the roster and that contributed heavily to Boston's postseason surge.

He implores his players to continually strive to be better and will implore each player to grow in specific areas this summer.

Your turn: Which Celtic player improved most this season? Sound off with your thoughts in the comments.