Fer joined Swansea on loan from QPR in February 2016 until the end of the 2015-16 season.
The 26-year-old midfielder made the move to the Premier League outfit permanent in the summer transfer window.
The former FC Twente and Norwich City man scored twice for the Swans in their 5-4 victory over Crystal Palace at the weekend.
Fer scored first in the 66th minute and then in the 68th minute of the Premier League encounter at the Liberty Stadium on Saturday afternoon.
Former Tottenham forward Crooks has praised Fer for his performance for Swansea.
The Englishman has included the midfielder in his BBC Premier League Team of the Week, and has suggested that the 26-year-old has become a better player since leaving QPR, who are playing in the Championship at the moment.
“These were two massive goals for Swansea for Leroy Fer, a player who I believe still has to fulfil his potential in the Premier League,” Crooks wrote on BBC Sport. “I saw a lot of him at QPR, but he seems more assured and accomplished playing for Swansea.
“He covers the ground and when required can put his foot in, but his ability to score goals from midfield is without doubt his biggest asset.”
Swansea are second from bottom in the Premier League table at the moment with just nine points from 13 matches.
The Swans are two points behind 17th-placed Palace and are in real danger of getting relegated to the Championship at the end of the season.