Ballin had a very important skill that Croker does not - good service from dummy half, our forwards looked miles better when running onto the ball from Ballin, compared to Monaghan before him, because his service from dummy half was quick and spot on.Manly's last 2 premiership sides featured a number 9 who was a tremendous player but definitely no Dynamic X-Factor out of dummy half. Fyi as starting hooker Croker scores tries at twice the rate Ballin did. Not that being a dynamic X-factor is that relevant in my opinion. Definitely it helps to have some in your team but they don't always have to be the 9.
Ballin is the best hooker we have had in our squad in the past 20 years. The only others who have come close are Fainu and Parcell - in terms of their ability to lift the whole forward pack by using the ball well.
Croker is a fantastic defender, which he and Ballin have in common, but he's not in the same league as Ballin at all when it comes to what you need from your hooker with the ball in hand.