Niemann is among the favorites to win this year's American League Rookie of the Year Award, which will be announced on Monday at 2 p.m. ET. Other top candidates include Rangers shortstop Elvis Andrus, A's closer Andrew Bailey and Tigers starter Rick Porcello.
Oakland lefty Brett Anderson, Toronto starter Ricky Romero and Chicago White Sox slugger Gordon Beckham are also contenders for the award.
It's already been an award-winning offseason for Niemann so far. Last week, Tampa Bay's local chapter of the Baseball Writers' Association of America named him the team's Outstanding Rookie Award.
Niemann spent all of Spring Training competing with Jason Hammel for the fifth spot in the rotation, and he didn't find out he won the job until the day before the Rays were scheduled to open the season at Boston. Hammel was eventually traded to Colorado.
Niemann went on to be one of the best rookies of 2009, but the road to success was not an easy one. The right-hander was hit hard in his first start of the season in Baltimore, giving up six runs on six hits in 5 1/3 innings in the loss. He finished April with a 2-2 record and a 4.43 ERA.
Things got better.
He threw the team's first complete game of the year on June 3 against the Royals when he won, 9-0, and went 3-0 in the month. He also went 3-0 in six starts in August. By the end of the season, Niemann had taken charge of his role of the rotation and finished 13-6 with a 3.94 ERA in 180 2/3 innings during 31 games.
"It's crazy how full circle things have come," Niemann told the St. Petersburg Times. "The humble beginnings and what really happened, where we are now. It's a great story for me to tell, and it never gets old. I still find myself kind of wondering how everything worked out the way it did."
Niemann led all rookies with two shutouts and struck out 125 batters while leading the Rays in wins. He walked 59.
"As far as from Day 1 compared to the last day of the season, I really transformed and grew a lot as a pitcher," Niemann said. "I learned more than I've learned in my whole career this year, due to the whole trial and error."
Whether or not he grabs the AL Rookie award, in some ways, Niemann is already a winner.
"I want him to go out there and pitch knowing that he doesn't have his best stuff, and just go out there and see if he can be productive," Rays manager Joe Maddon said at the end of the season. "A great lesson to be learned going into next season."
Jesse Sanchez is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.