Cohen took the summer off, removing himself from the British & Irish Lions standby list and making himself unavailable for the England A Churchill Cup tournament.
After a dogged season with Northampton that so nearly ended in relegation, Cohen needed time away from rugby to re-charge his batteries and recover his enthusiasm for the game.
The plan worked. Cohen returned to the England set-up in November after a flurry of tries for Northampton and last weekend he won his 50th Test cap in the victory over Italy in Rome.
"It has been a fantastic year for Ben," said Grayson.
'I am full of admiration for him. He has been very honest and open about how he has returned to the game and he is getting his reward."
Cohen, his England colleague Steve Thompson and Scotland winger Sean Lamont have all been included in the Northampton side to face struggling Saracens at Franklin's Gardens.
Lamont scored twice as Scotland beat France on the opening weekend of the RBS 6 Nations.
"It's nice to see them all doing well with England and Scotland," said Grayson.
"The teamsheet does read well but the boys coming back have got a fair amount to live up to. Some of the boys who played well last week were unlucky to miss out this week.
"Last week's 19-19 draw with Wasps was our best performance and we know this weekend is a vital fixture in terms of progression and I would like to back up last week's performance with a good game at home."