The Scotland international scored West Brom's second goal against their relegation rivals during an impressive performance.
Mel believes that Dorrans could have a big part to play for his team as he aims to secure Premier League survival.
"He is a magnificent footballer. He's extremely committed to the cause and his performances are getting increasingly better. He could be a key player for us," Clubcall.com quotes Mel as saying.
"Cardiff was the third game that he's played. He played at Swansea, Hull and barring anything going wrong he will play at Norwich. He's a player I trust in and he's performing very well."
West Brom currently sit 17th in the table, three points clear of the relegation zone.