The Argentina attacker has shone for Villa this season after working his way back from long-term injury.
"He had an injury for 10 months, and after he was training with us, he needed time to get in everything - good, mentally, physically confident," Emery said regarding Buendia's form ahead of Sunday's trip to Leeds.
"He struggled last year and all the season, firstly with us for six months, not getting his performance and not playing consistently and not feeling really good.
"When he was on loan in Germany, with Bayer Leverkusen, he didn't achieve his confidence. He didn't achieve minutes. He didn't achieve numbers to recover himself, like a player he is.
"This year is completely different. He started so focused. He started the season very demanding, getting fit, feeling confident, playing with his skills, showing in each match he played in pre-season.
"Everything that happened around him, he deserved it because he worked hard to recover his best form as a player like he had before he was here.
"When we decided to keep him here, and he decided to stay here as well, I was confident he could get the numbers he is achieving."