The Dutchman, signed from ADO Den Haag for £85,000 in June 2007, went some way to repaying the Swans fans with his second goal of the season, a fine 25-yard strike to put the home side ahead nine minutes before the break.
"He is a top-class player and he is capable of doing what he did today on a regular basis," said Martinez.
"We spoke about his decision enough and you can see he is happy, settled and focused and we all know he'll have a massive impact in the Championship."
But Martinez was less happy about dropping two points after dominating for most of the match.
Owls substitute Steve Watson salvaged a point for the visitors less than 60 seconds after coming on as a 70th-minute substitute.
The veteran rose highest to meet Marcus Tudgay's cross and headed home after soaking up the Swansea pressure.
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