De Boer believes that the 27-year-old will return to the form he showed during his time at Arsenal, describing the Spain international as "an outstanding player".
"He didn't really find his form and his freedom [at Barcelona]," De Boer told talkSPORT. "If you saw him play at Arsenal, he was a player you felt was really happy on the pitch. With Barcelona he couldn't really find his way. That can happen.
"In a team you have 11 players and sometimes the magic is not there [for some players]. With the change he can find his brilliance back.
"For me, he is an outstanding player and the Premier League should be happy that he is back."
Fabregas made 151 appearances in his three years at the Nou Camp, scoring 42 goals.