The Wales international has proved a massive hit at Hull – scoring five goals in 10 appearances to lift the Tigers away from the drop zone.
“That move was the right thing at the right time for him. He's gone there and he's banging goals galore in, assisting, winning penalties," Critchley said.
“He's gone to the Championship which is extremely tough. It's a war of attrition that league. It's Saturday-Tuesday every week, and you have to prove yourself every single game. You don't get a lot of rest.
"He went to a team that was down at the bottom of the table, and they've obviously picked up, won some games and he's contributed to that. He's proved that he's more than capable of playing at that level.
“He went away with his country recently and scored on his 21st birthday so he's been in a real rich vein of form.
“If you keep scoring goals, you get noticed. We're talking about him now, aren't we? He's in a really good place at the moment, and hopefully he can carry it on.
“He's had a fantastic start but he'll want to finish the season the way he is now and then come pre-season, I'm sure he'll be thinking of being in and around the Liverpool squad for next season."