Bony netted the FA Cup winner at Manchester United on Sunday.
"It took him a while to settle in," admitted Swans coach Alan Curtis.
"He scored a lot of goals last season but he missed out on pre-season with us so he was playing catch up.
"The fact he came for £12m meant people expected a lot from him, but he was just short of fitness and throughout the season we have worked on that.
"But his strength and power are quite frightening - he is a real beast of a man he already has 13 goals this season and his latest one was a cracking goal."
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