Most Improved: Simona Halep and Stanislas Wawrinka

With the 2013 tennis season in the past, it's time to dole out our annual awards. Look for the winners—for better or worse—throughout this week on TENNIS.com. (To see what's been unveiled thus far, click here.)

Simona Halep: The 22-year-old Romanian could also be called the Surprise of the Year. Not many experts, after watching her get throttled by Sloane Stephens—6-1, 6-1—in the first round at the Australian Open in January, would have predicted that it would be Halep who would end the season ranked one spot ahead of her opponent that day. Fewer still would have predicted that the spot would be No. 11, up from No. 47 at the end of 2012. And nobody could have foreseen that Halep, who had never won a tournament before this season, would win not one, not two, not three, not four, not five, but six WTA titles in 2013.

The undersized—she’s 5’6”—but hard-hitting Halep had her reverse Waterloo in Rome in May. Ranked No. 64 at the time, she won three qualifying matches, and then upset Agnieszka Radwanska, Roberta Vinci, and Jelena Jankovic before finally getting knocked back to earth by Serena Williams. But that loss wasn’t enough to shake Halep’s newfound confidence. In June, she won in Nurnberg and s’Hertogenbosch. In July she won in Budapest. In August, she recorded her best victory of the year, a 6-2, 6-2 final-round rout of Petra Kvitova in New Haven. Halep closed the season with titles in Moscow and Sofia, beating Sam Stosur in straight sets in the finals both times.

Halep, who had a sub-.500 tour record before 2013, says she tried to loosen up and play more aggressively this season, but even she never expected it to work this well. Yet the Most Improved still has room for more: While she was 53-17 for the year, Halep was just 4-4 at the majors. Nobody would be surprised if that record gets better in 2014, or if she gets a few more games from Sloane Stephens if they play again in Australia.

Stanislas Wawrinka: It’s a measure of how tough the ATP tour is these days that its Most Improved Player would raise his ranking by a grand total of nine spots. But while others, such as Grigor Dimitrov and Ernests Gulbis, made bigger gains, Wawrinka made his at the most rarefied, and brutally competitive, level of all: The Top 10. At age 28, after years of floating erratically through the second-tier, and playing second-fiddle to his countryman Roger Federer, this heavy-hitting shot-maker qualified for his first World Tour Final and finished the season at No. 8. The potential that Wawrinka had always shown, especially with his sledgehammer one-handed backhand, was finally fulfilled.

We should have known we were getting a different Stan after his performance at the Australian Open in January. There he reached the fourth round and, with Novak Djokovic, staged what may have been the match of the season. Wawrinka eventually lost in the wee hours of the morning, 12-10 in the fifth set, but he had fought the world No. 1, a man he hasn’t beaten since 2006, every step and swing of the way.

Wawrinka built from there. He had success on all three surfaces, and avoided the wild swings in quality and confidence that had plagued him in the past. He reached the final in Buenos Aires in February, lost a close match to Federer in Indian Wells, beat David Ferrer to win an event in Portugal, lost to Rafael Nadal in the Madrid final and the French Open quarters, made the final on grass in s’Hertogenbosch, and capped the season by shredding Andy Murray at the U.S. Open to reach his first Grand Slam semifinal.

It was fitting, if unfortunate, that Wawrinka’s Slam season ended the way it began, with a five-set loss to Djokovic (Stan also lost his last match of the 2013 season to Nole). Yet in New York he showed again that he’s not out of the top players’ league. Wawrinka’s coach, Magnus Norman, said that the goal in 2013 was to make him “stronger,” so he could compete physically with the world’s best—mission accomplished. Now for the next mission: Beating the world’s best. Wawrinka, for all of his improvements, is 3-44 against Nadal, Djokovic, and Federer for his career, and those guys stood in his way again in 2013. If he can get past them a few times next year, Stan might be accepting this award again.

Further reading:

—Video: Djokovic's match-ending point in his incredible match with Wawrinka.

—Steve Tignor's report from Melbourne on "The Nole and Stan Show."