Cole has proved a big hit at the French champs.
"He's a great pro," Sow told RMC Sports. "Along with [David] Rozenhal, he is the first in the locker room in the morning.
"He is always there ready, he is very involved and highly motivated, even when he's not playing. It's a surprise to see him like that.
"It was a gamble for the club, and so far it's been successful."