Success scored six goals in 28 La Liga games last season for Granada who finished 16th last season.
According to just-football.com, Success’ impressive performance last season earned him a place in the top 10 young players’list.
Success was rated 8/10 to join the likes of Inaki Williams of Athletic Bilbao, Jose Gimenez of Atletico Madrid, Sevilla's Sergio Rico and Dani Ceballos of Real Betis in the list.
"Tremendously raw he may be, but Isaac Success produced yet another impressive campaign for a misfiring Granada," just-football.com writes in their report.
“Again, all that explosive pace and skill were on show as he managed to produce six goals and two assists in 28 appearances in La Liga.
"He was regularly the chief architect and force behind Granada's attack, and showed he's able to take on more responsibility.”
The 20-year-old has left Granada, signing for Premier League side, Watford. He made his league debut for Watford in their 3-1 home loss to Arsenal on Saturday, August 27.