Agustien revealed he tipped off his agent about Swansea's search for a new keeper following the departure of Dorus de Vries after the club's play-off promotion.
"Me and Michel have the same agent so I mentioned it to him when Swansea were looking for a goalkeeper because we knew a good one!" Agustien told the Western Mail.
"And Brendan (Rodgers) asked me about keepers in Holland and I mentioned about Michel so it's great to see him here.
"I don't know if I helped, but Michel doesn't have to thank me, he should only be congratulating himself because he has done so well. I always knew he could do well and show how good he was in Holland in the Premier League, but he's been unbelievable."