Why wasn’t Nadezya Ostapchuk sentenced to two-year ban?

Nadezya Ostapchuk, a Belarusian shot putter, received the gold medal at the 2012 London Olympics. But she failed a drug test. As a result, she was stripped of the medal which was given to Valeria Adams of New Zealand.
Two tests showed that a steroid’s metabolites presented in her urine samples.
When a sportsperson is caught applying any prohibited medicines, he/she is usually sentenced to a suspension of two years. When it comes to this Belarusian shot putter, she received one-year ban. Why was the sentence lighter? There were some circumstances which proved the following condition: Nadezya Ostapchuk didn’t take any prohibited medication intentionally.
At the beginning the shot putter blamed his former coach. She claimed that he had sabotaged her sample.
The Belarusian National Anti-Doping Agency examined this case. The International Association of Athletic Federation assisted the investigation. It was defined that Yefimov was guilty. This person put powder of methenolone into food of Nadezya Ostapchuk during the last week before the 2012 Summer Olympics. The coach affirmed that he had worried about Nadezya Ostapchuk. He thought that this steroid would help to win.
In fact, it is difficult to understand why Yefimov has done it. He just made the things worse.
Anti-doping officials accepted these statements. That’s why Nadezya Ostapchuk received only one-year ban.
As for supporters of Valeria Adams, they didn’t believe that Nadezya Ostapchuk had not administered the steroid knowingly. They claimed that Yefimov just put efforts to protect Nadezya Ostapchuk. They confirmed that Nadezya Ostapchuk had taken steroids under recommendations of her coach.
If the Belarusian shot putter’s performance was great some months before the 2012 London Olympics, her coach had to be sure that she would win. Why did he trouble about?