"Jobi is a big talent and he gives us something different," Rodgers told the club's official website.
"When I was at Watford he was outstanding; he can create opportunities, has terrific speed and great technical qualities.
"He's a good guy in the group and, like all our squad, he wants to get back into the Premier League.
"Grzegorz also did fantastically for me during my time as Watford boss. You look at his record and he's a proven goalscorer and an experienced international.
"He is very, very strong and he scores goals. Both players will be very good for us."